Crafting, because from what I hear, crafting right now is... crafting for the sake of crafting something to be able to craft something for crafting. Something like that. They'll have to make crafters relevant again. Maybe even something to do with gathering. So those people who are already rich can get even richer.

Other than that... Crystal Tower, maybe, since those are pretty dead nowadays (again, from what I hear). Or even Extreme Primals.

And yes, definitely more RNG. Because there is not enough RNG yet, and RNG is fun, apparently.

Or cash shop.