You know that actually makes me think. That would make for a good Firefight gametype, where the enemy team plays as Grunts, Brutes, Drones, and Elites and such. I'd definitely play that.
To be honest I really didn't care that Elites were absent in Halo 4. I don't think it would be the end of Halo 5 if Elites were still absent.
I do agree it would bring in more Players if the Elites were present, but I think Halo 5 would survive without them.
Oh and do you know what those predictions are? Just predictions, not the actual path the Xbox One will take once it launches. For all we know the Xbox One could be the best console that Microsoft has shelved out yet, and be a best seller, or fail horribly. We don't know.