I don’t want to barrage 343i with a bunch of suggestions for game play. There are though a couple of small suggestions I hope 343i will read and take into consideration.
I honestly would love to see the return of the Hayabusa armor. Mega Blocks has been making Hayabusa armor Spartans for a while now (with usable Katanas!) A slight redesign would be fine, but keep the sword. If the katana chest piece is equipped it can be used for assassinations. Similar to when a player holds a sword, the assassinations will be katana based. The animations could be based off of samurai killing techniques (or something from movies.)
In fact, my next art piece will be what Halo 4 Hayabusa should look like.
The return of the Halo 2 ODST armor and various other armor sets from the franchise.
The Mark VII armor (I’m pretty sure the armor from the reveal trailer is Mark VI) should not be available as the default armor. I’m assuming that Master Chief will be wearing Mark VI at the very beginning of Halo 4. Once the UNSC shows up, they give him a set of Mark VII armor. So it should be that once you reach a certain level in multiplayer, you then unlock the Mark VII.
While I have many many other suggestions, these are the ones that I would really like to see in Halo 4. No big deal if 343i doesn’t use these, it’s just my personal opinion.