Well 343i did post something about community maps that looked alot better than what the so called Cartographers came up with, given the fact that they were the first to 'experiment with it' the maps fell kinda short. So I hope we'll eventually see some of those maps in matchmaking.
Besides those I'm hoping for some more maps that are built from the ground up, not remakes in Forge, not remixes of already existing maps, just brand new maps to play around with. (unless the remixes actually feel different like Overgrowth... but play way better than Overgrowth...)