Personally, I'd like an Adventure Map section on the game. On the sub-section, you could browse Maps appointed by Mojang, download them on the spot, and share opinions.
Some more skin-oriented liberties would also be nice. A may to make parts of a player-head bigger, along with the possibility to add in additional appendages. making something like the Xenomorph or a Villager might be neat.
My main hope is some spice for survival worlds, instead of belligerent updates adding in lazily made structures and new blocks, something like a grand dungeon would be neat. Maybe a castle full of pillagers along with really high-tier loot and secret rooms. Something like a larger Woodland Mansion
Best wishes :)