It could go a lot of different directions, yeah. I doubt they'll do something ODST styled, though.
Who knows what their plan is for campaign after the backlash Halo 5 received. I'd like them to either have a more radical departure like ODST with a hub world, or go back to levels like Assault on the Control Room and Silent Cartographer. I hope they don't stay the course with 4/5 styled levels as their general linearity and corridor level design are bad.
This is also true. H5 had some fantastic playspaces, the problem was the general lack of decent vehicle levels (though there were some good sequences).
Halo 5 has some of the best on foot level design in the series and if they move away from that I will be extremely disappointed.