Features:
New Grand Companies, I get this could be tricky considering how much of it is tied with PVP.
I think the best way around this is the PVP mode (like Frontlines) accounts for which has the most members of a Grand Company that is participating, and so that Company wins the ticket to be represented in that pvp mode and that way PVP always retains a 3-way battle system.
Maybe with new grand companies could come new types of PVP like 4 or 5-way battles.
I think Ala Mhigo would be perfect to have a 4th Grand Company (though maybe there is lore reasons why that can't happen)? Or Maybe GCs must be always be accessible to new players which means having a new GC wouldn't happen? Idk.
I like to think Grand Companies are still somewhat relevant in current content though it has weakened over the years.
Feature 2:
I noticed most of us players use a lot of dance emotes for a huge variety of RP stuff, I think it would be cool if maybe we get some more dance emotes at some point both for Mogstation and in-game rewards, but have dances not be too silly? Lot of RP scenes I've seen like to stick with Bee's Knees since it doesn't look nutty like some other dances (its the most used Dance Emote I've seen be used aside from Gold Dance).
Zones:
I think Gold Saucer is heavily due for some new fun stuff to do (well for years actually), like entirely new floor to explore with new mini-games and other things and maybe some throwbacks from the original Gold Saucer from FF7. Would love Ghost Square from FF7 to be a actual thing, and maybe import some things FF7 Gold Saucer had into FF14.
Personally I would love to see the Developers make the outside of the Gold Saucer be available to visit, we never truly get to visit it upclose aside from Southern Thanalan from a certain distance away
Gold Saucer needs a lot of love, and players still regularly visit the Gold Saucer everyday, so I think its worth a update and resources to consider one day.
I feel like there could be other zones that might need a touchup, but nothing is coming to mind right now.