I was discussing with a friend of mine how they multiplayer has become too easy to rank up and gain weapons, perks, etc. So to keep things fresh, why not increase the xp required in each prestige to level up, and make it possible to prestige only after completeing certain challenges. Also why not make some guns unlockable a certain prestiges, so there is more of a variety of weaponry as you go.
Increases exp requirements will only make things more tedious
It would be more rewarding though, and make it you feel more acomplished when you're a higher rank than another player.