I get tired of seeing these threads when a new game is announced (or sequel). We know just about nothing, there has only been a trailer (a teaser at that) and a couple of interviews about Chief coming back and what have you.
Other than that we have no clue what is happening.
Don't worry, your not the first. Bioshock Infinite, Hitman Absolution, The Darkness 2, Prey 2, etc, have all had people jump to conclusions before any actual info is released. Let it run it's course, who knows, it may be the best Halo yet.