Persons who think this is going to suddenly jump from 720p 60fps to 900p 60fps over a year are fooling themselves, something has to give. Since Halo5 is going to be a new game on new hardware, they will try to push more effects, use more advanced graphical features and that will task the hardware. People should really turn off the blinders, Halo 2 anniversary runs at a lower resolution than even 900p and that's basically a remaster of an old game, yet, it still dips quite a bit from 60fps in the campaign.
Halo 5 will not be running 2 engines like Anniversary and have MUCH more resource being thrown at it. And we've seen many games jump from 720 to a higher res with a late patch (COD, AC4) a year dev time its more than reasonable to assume things will improve drastically. I cant think of a game that has remained the same/similar visually a year before release....