Edit.V.1.1 (have to incorporate a few great ideas from players in this thread still)
TL;DR Only read the bold parts.
Hello Yoshi P. and FFXIV Devs, As someone who has supported FFXIV since its original launch and one who went to school for Game Development I'd like to take a few dozen minutes out of my day to give some suggestions that I hope you read so that maybe one of them will help you shape the world we all enjoy and love.
1) While the current housing scene is functional as a place where you can display furnishings and hang out with friends, it lacks the feeling that housing would typically have; Community. Far more often than not there is little to no engagement with your fellow residents and neighbors, making the purpose of an entire ward of houses rather than a completely instanced experienced rather unclear at best. With this in mind you would have two options to remedy the issue, either A) Do away with wards and shared area housing completely and opt for purely instanced based housing, which has the benefit of ensuring that 100% of players would be able to own a house, or B) Make the housing districts feel alive. To achieve this would be a somewhat simple task truth be told, and some of the techniques used in this could also make every other city and area feel alive as well. Option B is the option I will expand on as it has great potential and would improve the experience, rather than option A which would simply destroy it.
To begin with let's look at something simple. In this patch, aside from adding Shirogane, you also added swimming to every area and along with it you added NPC's that randomly sit around in the water swimming. This is the launch point for this "alive" feeling I'm speaking of. NPC's play a crucial role in making the world of Hydaelyn feel alive. Adding NPC's within city and sanctuary areas provides a feel of activity and liveliness, but having them stand in one spot while repeating a very small loop of animations can actually create quite the opposite effect. Rather than these small loops, if each NPC had a twenty-four Eorzean Hour schedule of set actions, where they walk from place to place, chat with other NPC's without text bubbles, disappear into buildings from time to time, these things would create that aforementioned feeling of life. Add to this interactivity with NPC's, where at set times per Eorzean day they sell exclusive or discounted items, repair gear for a reduced price, affix materia for a reduced price, etc, players will engage with the zone more and travel around the estates for these boons, bumping into one another and perhaps chatting, eventually making new friends.
Additionally, there currently lacks much of a point for players to go around to another player's housing and either tend to their crops, feed their chocobos, or simply engage any house that is not their own. The reason for this is that Players do not benefit from these actions in any way whatsoever. By nature the human species has a desire to not waste their own time, and while helping others is a great thing we all strive to do, if we obtain nothing for it then it is disadvantageous to spend time doing it. I would propose then that upon doing beneficial actions for other players, either by tending to or fertilizing other players crops, feeding and training their chocobo's, or perhaps in new and other unique ways, players would then obtain an amount of tokens based on the action in question (actions that require the player to use items of their own would give a higher yield of tokens). You could then create an exchange system with the NPC's of the zone for exclusive items and use these tokens used as the currency (perhaps used for all exchanges between them?).
I am aware that based on lore there is little reason for NPC's to be in these housing districts as they are designed to be used by adventurers only, but that does not mean that NPC's can't have jobs that they work there, giving the Adventurers the quality of life that is expected in that area (for instance cleaning the walk ways, tending to the grass and plant life, selling cuisine, etc). If you were to utilize this system I can assure you that players would not only enjoy it, but use it immensely.
2) While I know not the limitations of your current servers I do know that players can load vast maps and effects on their home computers. As the years advance this will only become a more and more true statement. I believe that at this point players can quite easily load the housing areas and have a large amount of RAM, Video Memory, and Processing power to spare. Add into this the fact that there is already item culling wherein once far enough away/if there are too many items at once, the furthest of them don't render any longer, which takes a load off computers as well. That is why the limit of only thirty houses per ward is somewhat crippling to a community atmosphere. A residential area in the offline world is expansive and filled with many of the same kind of house/amount of land allocated per house. While having three different sizes of house is appealing, I believe that in the current set up it actually strains the amount of players you can give housing in each ward as well as taking away from a feeling of progression with your house itself, simply paying Gil to erect the final product. The solution to this is separated into parts, but in this point I only wish to posit that there could and should be more houses, perhaps sixty to seventy-five houses per ward. If that means making a bigger and redesigned map, then so be it. Additionally, if you were to do this the need for a subdivision per ward would be eliminated, adding to the community feel as players in each ward wouldn't be separated by an unnecessary instance.
3) The second part of this then comes to the house sizes and what would happen to current residents if they were to be changed. First and foremost, the player should be buying a uniform plot of land, not a specific house/plot size, which would be separate from the size of the house they will build. I would suggest that players are given the option of what size house they'd like to build on their plot, which would also mean that they can always upgrade to a larger house later on when they have more Gil/resources. The sizes of the plots should be slightly larger than medium plots, but smaller than large plots, all being the same in price (five to ten million gil?). Players would essentially be able to choose between having a large house and small yard, medium house and medium yard, or a small house and a large yard. There would then be Gil/resource prices based on the size of the house they desire, equating to nearly the current price of houses in the end. This gives a great amount of customization to the players, customization I believe they would enjoy immensely.
4) With the previous two points in mind there would then arise the problem of the displacement of current residents. One could even call it the Housing Calamity. If in the event the team decided to change to this system or even going so far as to create the larger map, there would be a simple solution for current residents. Refund them 100% of the price they paid for the original house, then allow them to directly purchase a plot in the same ward they were in before any other purchases by non-residents can be made. This "Reclaiming" period of time could last for at least a month, perhaps two, after which the remaining new houses would go up for sale to all players. This would allow the new system to be in place while not neglecting nor upsetting the previous residents. Furthermore, it is a well known fact that fake/alt/secondary FC's and Alt characters acquire multiple the houses in the housing districts. To alleviate these issues, if you were to make the housing system tied to a player's account rather than a character of theirs, this would prevent them from purchasing multiple single player AND FC houses per character in a world server and would free up quite a few houses to other players. As for whether a plot is single player housing or FC housing, I would suggest that FC housing be an entirely separate experience.
5) You see, even though this would be an improvement on the current housing system, it still leaves many without the opportunity to purchase a home as until dynamically generating and culling wards can be introduced there would always be a shortage. That is where Ishgard would come in. There's no housing district for Ishgard because they are opposed to outsiders, perhaps less so in recent times yet still enough to not desire a flood of adventurers into their city. But what if they didn't have to? As we all know, not all that far from Ishgard are certain lands that are more unique than most. I talk of course about the Sea of Clouds and Churning Mists, where land floats within the sky. Perhaps if Ishgardeans were to stumble across a large amount of floating rock and shear it into large plot sized land, players could reside on them! Indeed, this would be beneficial to all and form the phased instance housing. Just like apartments there can be a vast amount of these houses, all independent of one another. FC's and single players alike would be able to purchase a floating slab of land to build upon in their respective sizes. You could visit the houses just like apartments to ensure that players in this "district" would be able to accumulate the benefit tokens without traveling to one of the other four housing areas. This would create a way for a vast amount of the player base who miss out on buying or being able to afford a house in other zones an opportunity to still become the proud owner of a place they can call home.
6) Finally I come to my last main point. How would players be purchasing houses? To this I only need say one word, Auctions. If houses were to run on an auctioning system it would give all players a chance to snag their favourite housing plot. It is a simple system to create would make a great deal of players extremely happy, even if only because it allows them a chance rather than having to deal with post patch login issues and losing their chance altogether. It should be noted however that as players can only own one house per world based on their account at this point, any who already own a house would be unable to place bids. Furthermore, when bidding the Gil must be deposited directly into a vault at the plot in question. When the auction is over players will be able to obtain their gil again by visiting the Vault Master(?). Ishgard and Apartments could still follow an instant purchasing model, as the amount of these available is already vast in size. If a player is outbid they would be able to either go withdraw it from the vault and bid on another house, or add more Gil to the vault and outbid their current contender. Additionally, when a house is being demolished there should be a notification option that players can opt into, either sending them a cute moogle-mail in-game, which would also be the same method that players are notified about their bids.
Overall I of course do not expect all nor any of these ideas to be implemented, but if any of you on the development team read this I would implore you to consider them and to use them in your creative process to find the ideal way in your own eyes to improve the housing in the game going forward into the years.
Happy Adventuring everyone and may Hydaelyn's light always guide you.