Just looking at what they've changed in Matchmaking since release gives me hope for Halo 5. They took out random global ordnance while adding on-map weapons, reduced the frequency of Infinity in all relevant playlists, released more arena-sized maps, added an actually different gametype (Ricochet), and took out all but one single-objective playlist, implemented 4-shot BR (but 150% SAW is absurd). If they keep going in that direction, I think it actually might be okay.
But they also have recently done dumb things like make Legendary AR's and Beam Rifle slayer (and buff the SAW in Turbo, wat), so I'm not Ozzy-ptimistic, just sort of hopeful.