Predicting The Next 12 MCU Movies After Avengers 4
5. Thor: Siege
Assuming Thor isn't killed off in Avengers 4 (let's hope not, given how popular Ragnarok was), there's some big unfinished business for the God Of Thunder and that could make for a great fourth movie.
Predictions
As established in Thor: Ragnarok, Asgard is no more and Thor had planned to bring his people to Earth to resettle - as happened in the comics. That sort of thing would inevitably cause friction (and a big opportunity for a pertinent commentary on immigration culture) and could be the focus of a soft adaptation of the Siege comic book event.
It probably wouldn't be a pure adaptation (but when do Marvel ever do that?!), but having a villain rise up to protest against New Asgard's appearance on Earth as a threat to national security (and plan an invasion) would fit with the fact that Thor was the original threat that inspired the Avengers Initiative.
Evidence?
The unfinished business of the surviving Asgardians has to be dealt with in some way and Siege offers that opportunity with added drama. It's also one of those popular arcs that Marvel Studios tend to gravitate towards when they look to adapt.