I think he's dead, but I could see him coming back. If they want to bring him back, the next Avengers movie makes the most sense. And, it'll depend on if they want to go that route. The "death" was left ambiguous, which allows for bringing him back (especially given the deceptive nature of Fury), but I don't think the intent when they wrote the scene was to have him alive. I'd have no problem if he comes back. It would make for a kickass moment.