Excellent topic. I'll break my ways to address how I would prefer to see summoner reworked as well, keeping in mind that with how every time SE has reworked a job, they like to keep current assets and thematics. As much as I'd love to pull a Yuna from dissidia or start looking like the mc from XVI and use dynamic attacks that bring about the summons arm to smack an opponent with each strike, I don't see that as a realistic hope for the dev team to pull off. Instead my proposed rework aims at keeping current assets, keeping the same feel that summoner has of fast paced mid to high APM play, and fixing the leveling and learning curve of the job for newbies, all while removing current frustrations that upper level players have, and primarily focusing on what brings the most hype factor to the job, the Demi Summons.

Egi's:
-I know many will disagree but I would like to see Egi's removed from the top level summoner rotation. Flat out, having played summoner as my primary caster since 2.0, I've seen every Egi rework done, and not a single one of them were ever able to address the issues I had with the pet AI in this game. Many of them actually just made it flat out worse. So I would like to see them removed from the soon to be level 90 rotation that is coming in 6.0. While I would love to see the dev team find a way to make pet actions work in this game PROPERLY, after 8 years and 4 different reworks, I have lost faith in them pulling it off. I DO NOT however want the Egi's axed entirely, as there is lore reasons and purely aesthetic purposes to keeping them around. I will touch on how to keep them around in my next part. The loss of egi-assaults and their generation of Further Ruin will also need to be addressed which I will put my thoughts on later.

Leveling experience:
-Let's face it. Leveling summoner from the ground up is an absolute mess for a new player. Heck even starting at 70 doesn't feel great. From step level 1 to 30 to 60 to 70 to 80, you are essentially playing a different job. This creates a very disjointed experience for new players, and also makes getting level synced down a miserable experience for veterans. This is where my idea on removing egis' from the upper level rotation but still keeping them comes into play. Make the egi's the mini versions of the demi's and have them summoned in a similar way, where a player brings them out during their burst rotation, rips off an enkindle or two, then lets them go. As you level up to 70, 80 and soon to be 90, each Egi will be upgraded to a demi. Ifrit becomes Bahamut, Garuda becomes Pheonix, Titan becomes.... whatever the heck they plan on adding (Alexander or Shiva would be my wishes). I also would then say for pure aesthetics, you would be able to still summon your egi outside of combat like a minion. I want my carbuncle still following me around the city. I'm just done with it ghosting actions in combat.

Trances:
-With the likely inclusion of a new summon (this section can be completely ignored if a new summon isn't getting added, as could probably every post in this thread, as we pretty much all expect a new Demi), the length of the summoner rotation once again must be addressed. My proposal for that is to tighten the trance cycle in time overall down to 12 or 15 seconds (changing enkindle to a 10 sec cool down to ensure you are still getting 2 off in a trance), and lessen the time between trances to either 25 or 40 seconds. This will either keep the summoner on their current minute long burst cycle, or move them to the 90 second burst cycle that monk and Warrior (and Bard kinda) share. Obviously potency's and tri-disaster/DoT timings will need to be addressed to keep this balanced. Also, to make the opener more seamless and due to the egi-assault loss, it's time to merge Dreadwyrm Trance into Bahamut, much like Firebird Trance works with Pheonix. So we don't miss out on the awesome Deathflare animation, I would also love to see Deathflare turned into a GCD replacement much like Brand of Purgatory does for Phoenix. I don't want to see DWT become TOO much like FBT though, so maybe instead of Pheonix's 1-2-1-2-1-2 cycle, Make it a 1-1-1-2? Or heck maybe just let us spam Deathflare over and over again since this hypothetical would be a shortened trance cycle anyway, it would give a really amazing feeling to the summoner to slam death flares into their opponent while bahamut hit's em with two akh morns, it would have the same feel of Savage Shiva or Nidhogg where they just hit you over and over again with Ala Morhns.

Demi's:
-Since we are merging Dreadwyrm into Bahamut and losing egi-assaults, mobility becomes very important. And while everyone and their mother sees all those free GCD's summoner has, any good summoner knows that your mobility is very much hindered by the Demi's constant need to follow the player like a lost puppy. So please, un-teather the freaking Demi from the player. This should be the one suggested change that shows up on everyones list. Make it so wherever I bring Bahamut of Phoenix out, that sucker stays right there and goes to work, allowing me to then move around the arena and handle mechanics with no fear that I'm missing out on vital wyrmwaves or scarlet flames.

Further Ruin:
-Under this rework, we obviously lose egi-assaults, and therefore our primary way of granting Further Ruin stacks for use of Ruin 4. While I also believe that Ruin 3 is due for a visual upgrade, I don't think it's time for 4 to go away, and because of that, I think we need a new passive trait that grants Further Ruin so you still have free GCD's during your down time phases between trances. My current thinking is either you build one for every two or three successive Ruin uses, with a max of 4 to 6 possible, or instead, place it on a timer, similar to how White Mage lilies work. The exact amount or timing of these is up in the air, as I would think the player base would need to get a feel for the job first to know how fast they should generate without it being too much of a crutch, but also generates just enough that a truly skilled player would always have as much as she or he needs.

DoT's/AetherFlow:
-I will also diverge from the opinion of several here and say I do not want to see DoTs leave summoner. XIV is already preciously slim on DoT classes as it is, with Bard and Summoner being the only two currently with more then one DoT to keep up, and that should stay. Forking those DoTs over to another new job somewhere down the line does not work either. How we interact with those DoTs though is certainly something that could be reworked, and I feel like it's best to instead look at the Aetherflow actions generated from Energy Drain/Energy Siphon and how those really gate our play. Summoner already suffers from extraneous button bloat, and XIV has a much better way of handling multiple actions with different applications for AOE/ST in charged actions. So I vote to remove both ED and ES, and put Fester and Pain Flare on a charged action system with a shared cool down, with the amount of charges and cool down keyed to insure that the job will get the same amount of oGCD actions in per minute as they do now with the current 1, 2, 3 of Energy Drain into Fester x2. Tri-Disaster resetting upon each summon is something I like, and would prefer to seen remain, with the application that it lasts long enough to just make it so that if a player is keeping up with their trance rotation properly and not dying, manual dot casting will be at a minimum.

Extra Bits:
-Make devotion cast from the player, not the summon.
-Upgrade the animations for fester and pain flare