I'm kind of getting tired of the whole "Hey, lets trash Halo because it's popular and then we'll seem cool because we dislike Halo" attitude. I'm not saying that anyone on this thread is doing that, but I am getting tired of people else where on the Internet gripping about the poor story and sameness of the past few games.
Most successful games have either or both of two things, great story or great game play. Halo's story telling isn't exactly Firefly or Stargate quality, but it's game play is rock solid. That's all that is needed to create a good game. Super Mario Bros. wasn't exactly telling a story that would have impressed J.R.R. Tolkien, but it was...wait for it...FUN TO PLAY.
Yeah, you might score some cheap "cool points" bashing the big mean franchise. I'm really into MMORPGs and sometimes I get frustrated by the fact that smaller games that I liked such as Asheron's Call and Dark Age of Camelot never got as popular as World of Warcraft, which I'm not a fan of. However, I can understand why World of Warcraft did better then those other games and accept those facts instead ranting about the negatives of WoW. If you want more people to play the games that you like, focus on the positive of YOUR games and not on the negative of the game(s) you are trying to get people away from, because it almost always sounds like an insult when you tell people the game they like is stupid.
Thats my 2 cents, anyway. I'd agree with others on here that a new IP from Bungie would be interesting.