A link to the past.
GTA6 will inevitably happen- presumably not any time soon, because all hands at Rockstar are currently on deck with the development of Red Dead Redemption 2, but a new GTA is inevitably coming- after all, GTA5 is one of the highest selling, most successful video games of all time. You have to think a sequel is en route sooner rather than later.
The on thing that I hope the new game allows for more than the last few titles have is more leisure activities- this is an area that San Andreas especially shone in. You had an entire set of secondary statistics for your character that didn’t really amount to much in primary gameplay, but were tied to a whole host of secondary activities, such as going to the gym, or getting haircuts.
And what was the point of those activities? Nothing, they didn’t actually add anything- but they helped flesh out the game’s world, and make it seem far more real and authentic. Now, GTA5 especially does really well in this regard, but it definitely lags behind San Andreas, which managed to be far more full featured and robust in these regards over a decade ago. Heck, take the drug dealing game from Chinatown Wars, flesh it out, and bring it back.
So, yes- we obviously want better shooting and driving, and a bigger map, and an epic story, and all of that, for GTA6. Obviously. Plus we want the satire and humor the series is known for, we want it to do everything these games do, and more of it. No arguments harbored on that front. But one area where I hope Rockstar adds more to the game is in the side activities. Add more texture to the world for the player willing to discover all of it.