Focusing on one of the things, and hypothetically speaking, if we are looking at ending housing for the micro FCs (that is, FCs that have 3 members or less) as IMO FCs that have less players than the number needed to create the FC shouldn't have a house, we need to look at why a player wants to create the micro FC in the first place. Speaking for myself, I would be inclined to have a micro FC if I was actually playing multiple characters on a server as having that swap space is insanely useful. Likewise, given how locked down gardening is with most FCs, I imagine enough players would like to garden but they'd need to have a house so they can cross garden. Then there's the workshop, and while (honestly speaking) I've got enough stuff to do in game so haven't really looked into it much beyond helping others craft stuff, I imagine for some they'd like to make use of the voyages without having to get permission to launch it, or having to negotiate with other FC members to go farm a specific node to get a desired drop.
That's kinda where the suggestions for letting all alts on the same server have access to the same personal house the server (and for that matter, letting the grandfathered in houses appear on each character that's on the same server), that negates one of the reasons for the micro FC. Same can be said for having a public garden system (real world example is https://www.fuhlsgarden.de/ btw). Workshop public access seems like that would need to be tied with us players getting something like a GC mobile squadron headquarter (as that makes the most sense for us getting an airship house), and we'd need to do that as a collaboration with Galrond Ironworks or Skysteel Manufactury. And if we're going to be building one airship... we might as well be able to build out a fleet of them so they can run missions for us - which provides a reasonable way for players to get access to the workshop outside of the FC (with enough work put into it). The other advantage to that system is if airship had required maintenance that was funded by gil, it would bring in a much needed gil sink too.
Speaking of gil sinks, attaching a maintenance cost to the house (functionally a weekly rent cost) that will condemn a house when it's unpaid and bar anyone from entering it (and thus making it unable to reset the AFK demo timer), but also allows you to prepay out like a month or two in advance. Players should get moogle mails when the prepaid rent expires, and also when a rent payment is missed so they are aware of missing payment. While this is also a mechanic from LotRO's housing system, it would also add in a much needed gil sink to FFXIV, as there are not enough gil sinks in FFXIV IMO - which is why I think it's needed in FFXIV.
That's a few suggestions, but it also (hopefully) sheds some light into why we can't just go straight to stripping houses from players and must instead tread a bit of a windy path before we can seriously look at that option.