Interesting guess but Truth was on that ship too so MC would own him.

Look in the background, that's the new mombasa bridge. You're in new mombasa after you've warped out, done delta halo and travelled back (possibly in time) on truths forerunner ship. When you go to slipspace in the atmosphere, it sets off a nuclear explosion, hence the nuclear wasteland he's walking though. IT's not the future, if anything it's the past ("i know your past, [u]your future[/u]")

its not the future or the past its the same time, notice all those convenat ships. yea they were there before master chief left earth so unless the entire earth time traveled they are in the same time. why would they change the time setting? mc would have no marine backups. if they went back in time the other prophets would be alive. do you think that bungie would have you kill one and have the flood kill the other just to have the come back? c'mon ppl lets THINK

Exactly: Truth's ship just used slipspace. Apart from the VCR needed to be reset, everythings fine.

my guess is that master chief will go back in time in the era of the forerunners. The forerunners are busy controlling the flood and master chief will assist them with containing the danger and he will be the cause of the activation of the rings. the gravekeeper or whats his name will be seen and guilty spark. that would explain their weird behaviour and the confusing things they say. and the quote that cortana made in the trailer i know you, your past your future. she has been told by the gravekeeper. And to back my story up, this all happened in their previous project Marathon and halo is basically a remake.