It seems like the character's future is up in the air.
Tom Hiddleston's contract carries him through the third Thor movie, and after that it's all "up in the air". This article from the Guardian argues that a solo Loki movie (maybe something like DC's upcoming Suicide Squad) is exactly what they need. And maybe they're right, maybe a solo villain movie would be a great move for Marvel at this stage. But should that villain be Loki? Especially if Loki is played by someone other than Tom Hiddleston?