Here is a bigger question... If Halo 2 Anniversary does get announced, and it is released for Xbox One only, will we get a first look at the engine that Halo 5 will be built on? I mean, if they build it like Halo:CEA and give it a graphical overlay... then I think you get an idea of what is coming, not a complete thought or permanent idea... but an idea nonetheless. Since the rumors state that Halo 5's beta will be on H2A... they could very well be using the same engine; and if H2A is on Xbox One, then imagine this: the multiplayer, if they bring it in, could potentialy run on the same engine as Halo 5 which could also potentially give you an idea of the Halo 5 multiplayer.
To lengthen the hype train even more: lockout, warlock, desolation, foundation, midship, Zanzibar, turf, sanctuary, etc.
Even if only 3 of those are included... I will be a happy guy.
However, since this is all a Rumor, I will patiently wait until E3 to see what comes of it.