I think some of you have unrealistic expectations as for as innovation in future Halo games. Most of the major innovations to the series were because of new tech/hardware. Look at Halo CE. It didn't do anything that PC shooters hadn't done really, but because of the Xbox power and dual analog controls it showed first person shooters could work on consoles. Halo 2's major addition was because of Xbox Live. Bungie took that technology and made a easy to use, well designed system to play games online with people. Halo 3's Forge and Theater were because of the Xbox 360's huge power increase over the original Xbox. Neither ODST or Reach did anything new honestly because they were on the same hardware as Halo 3. Yes I know ODST brought Firefight, but that was just an improved version of a game mode from Gears of War 2. If it was so simple to come up with new ideas that change the game, they wouldn't be so rare. A lot of times that stuff happens because of good timing, which was the case with many of the innovations Halo brought to the table early on. I'm not trying to say Bungie doesn't deserve credit for what they did, because they definitely do deserve it, but a lot of it had to do with timing and outside forces.
For anyone expecting huge new gameplay changes, honestly what addition to the gameplay has made the game better since Halo CE? Dual-wielding? Nope. Equipment? Negative. Armor Abilities? Definitely not. Most would agree these changes have all been for the worse. After 10 years though, what can you really add to change the gameplay that will make it feel fresh, yet still feel like Halo? The series has been around long enough where you have an established idea of what it is, and if you change much more, it's no longer Halo.
So basically the point I am trying to make is, that you can't really expect major changes for the series at this point. Hardware upgrades in the future won't be nearly as significant as what we have seen in the past, and the gameplay at this point has an identity you can't really change.
I don't mean this as a diss to 343 and it will probably come across as one, but you can't really expect them to do a whole lot new. For reasons I've already stated, and because they were put together for the sole purpose of making Halo games. They can't dramatically alter an established brand.