I really like this idea, though I think it's unlikely that they would implement it due to the development resources required. I like the idea of an instanced housing system alongside the current wards (kind of a 'best of both worlds' option) and I've often thought about how versatile instanced housing could be. You could purchase upgrades without needing a free plot, and they could continue to build on it, adding all kinds of cool stuff that just wouldn't work with wards right now based on how they are implemented. It'd be amazing to have something like this but in a small, expandable neighborhood, where your friends could still live nearby. Really, that would be the dream.

I'm holding out some hope for Ishgard right now. If there is a housing system, it's going to be tied to the endgame content for crafting and gathering somehow. Unless that content is some kind of server-wide effort, having it unlock the same old wards feels... awkward. It would make more sense to me if we get to a certain point with the restoration and were given the opportunity to build and/or purchase a personal house that's instanced. But we'll have to wait and see.