The Last of Us Part II: Is Joel Dead?

With The Last of Us Part II being announced at Playstation Experience yesterday, a new popular theory has popped up on the internet. Now we will be discussing it and determining how likely it is.

The theory is that Joel is DEAD and was killed by a group and Ellie pledged to find and kill everyone of them. The Joel we saw in the trailer was in fact a hallucination. But it seems that Troy Baker has a major role in the game, so some could assume that this theory isn't real or likely. But Joel could be like the Joker in Arkham Knight, a hallucination who sticks with you, and perhaps even terrorizing you. Or it could be like Obi-Wan Kanobi, a mentor who guides you throughout. This would make sense, since Ellie would be broken and almost shattered. What do you think about this theory that Joel is dead?