From Entertainment Weekly’s interview with Kevin Feige:
One criticism you’ve gotten is when somebody dies in a Marvel movie, they tend to come back in some way. If it happens, will it be for real this time?
Yes. I mean, I could always list off the characters that we’ve killed in our movies that haven’t come back, but the big ones, which I know they’re looking at …? [Pause.] I would just say, yes. People need to be careful what they wish for.
Loki is so, so dead. I just hope he’ll have a chance to do some cool stuff before he dies. And that he’ll die doing something epic.
Loki is the Philosopher King 