By the power of truth, I, while living, have conquered the universe.
I trust Bungie enough to say they know what they're doing. And personally, I'm really looking forwards to Halo without the comfortable powers of the Chief.
It's inevitable that gameplay will change and it is becoming quite dramatic now, just know that more tactical-esque play is what the majority of the community have been asking for. That's why we're getting ODST, that's why I'll be buying Reach next year and indeed any other Halo game coming in the future.