I'm fairly certain that Loki's story in the MCU is done in terms of character evolution, but I do think he was situated in a way that means he can pop up effectively anytime as a plot device whenever writers need one (and I'm fairly certain Tom will always be down for a cameo). Which is interesting with Young Avengers obviously being lined up.

Like imagine Loki being somehow instrumental to forming a second team of Avengers, but this time the intent and context is completely different. Not a villain to rally against, but a god guide though time and space? The irony of it, the circularity.