Err, Uh... That's kinda like saying we'll be able to play as the prometheans in Halo 6...

Well, look at Halo CE to Halo 2. The Elites were giant reptilian Dino's that we committed a small xenocide on, but with the gap between the two games came some novels and further background info about them, making them more sympathetic, and li and behold, when Halo 2 came out we got even [i]more[/i] with the elites, and got to play as them for the next 2 games. It's not as far fetched as you might imagine to play as the Fallen in De2.

See, the Fallen seem a little bit less Human-ish. The elites, despite their stature, still had two arms all the time, not to mention that the Fallen come in many different varied sizes, where as for the elites the only differences between them were the armor. Not to mention, Destiny itself is very focused on Guardians, and more so than Combat Evolved which really only gave you a brief synopsis. And, idk, I feel as though the Bungie team now is not the bungie team ten years ago, and would more than likely shy away from that kind of creative thinking, but idk, maybe they'll prove me wrong.