"Of course Master Chief didn't die. Wouldn't it be pretty foolish for Microsoft to kill off the only character they have?"
It could easily be that they had chosen to kill him at the end of HALO 3, since there has been no new announcements on the continuation of the series after this chapter. All that I have heard points to them ending it entirely with the third part, which we are all playing now. So to me it could be a probable, though sad, ending to a great videogame franchise. But then again, you never know what they really decided for next, deep within Bungie headqarters! I repeat that all I have read indicates a definitive ending to HALO. I hope there will be a fourth chapter, as I can vividly imagine even greater conflicts arising from sudden unexpected encounters with surviving members of the Flood, controlled by an even more angry Gravemind.
It might seek to throw an even more deadly enemy at Earth, or somehow provoke the Brutes into attacking the Earth. "One strain can destroy a species" one of the Elite´s leaders remarked during the course of the game. Would seem odd, though, since they have in effect killed them all (or so it would seem by all means) through the detonation of the Ring. However, Flood starins could have been blasted into the Ark through the open back of it, and attached itself to the insides of the ship without Cortana knowing it. She was corrupted by the Gravemind, wasn´t she? It is going to be interesting to see what Bungie comes up with next. But videogame story telling makes virtually anything possible,