I'm hoping for it. Assassinations bring a bit more of a challenge to the multiplayer experience. You've got to think to yourself "Can I actually get away with it on this guy?" There is no other feeling quite like when you pull off an assassination on someone who is standing right next to their teammates, and end up with a triple or overkill.
Also, for the record, I'm against AA's being in Halo 4, but wouldn't mind some armor customization for it's multiplayer.