I personally think that they should keep halo 4 original then they should come out with another ODST and experiment
the hell outta that. I mean i could care less as long as i have halo 4 to go back to right? Add iron sights bring back the smg
make some weapon attachments (not grenade launchers) if it fails say they could just say it was an experiment and halo 5 could remain the same
If it gets huge there's a semi new franchise that they could higher a new company to make idk
if they do make ODST 2 the definitely should get very creative with it
but overall Halo 4 needs to be a mix of 2 & 3 with sprint that's just my opinion