I believe elites should return as more than just playable, but hugely customizable.
Considering the concept art that appears to be Sangheilios, and that Halo 5 is going to be on the next generation console, I don’t see any reason why we should not be able to play as elites.
Also, I (heard that the game may be an open world) know it may be difficult to add them into the game, but I can’t think of one person I know who doesn’t miss elites.
If they aren’t playable in campaign, at least let us play as them in multiplayer and online.
