I had a thought while sitting in class(college).
Since Halo 5 Storymode is Co-op dependent, why not add a new firefight mode or a firefight,warzone,spartan ops hybrid where a team defends marines and bases and cores from A.I enemies.- This is what I thought about the most
I also remembered Headhunters in Halo Reach. I think that gametype or a similarity of it should make a brief return.
While watching A.H. playing Rainbow Six, Assault should make a comeback. It would be fun to toy around the idea of playing Rainbow Six style Assault where a team have to either plant a bomb or stop an enemy team from planting a team and each person only have one life.
Gravity Hammers should make a return for the return of Grifball and Skeeshoot(Reach) or substitute Grifball for American Football Ricochet.
If Infection makes a return it should make a classic infection return and the Halo 4 Flood Return.
Since forge is out, why not populate each playlist with remakes of old maps(hemorrhage, beaver creek, pit, sword base, lockout, and etc)? Just make a poll to see what remake of maps, players would like.
Since Halo 5 still contains Tactical and Support Package, why not add all or most of Halo 4 packages(Survivor, Gunman, Wheelman, and etc)