MCU Phase 4: 10 Biggest Challenges Facing Marvel Studios
7. Finding A Threat As Big As Thanos
Six infinity stones, strength and endurance similar to that of the Hulk and, most importantly, the ability to do what no other villain has on-screen: triumph over the Avengers. How could any other threat compare to Thanos?
Doctor Doom comes to mind when thinking of villains that could possibly compete with the Mad Titan; yet Doom would only be able to match the devastation caused by Thanos if he repeated the same plan. The Annihilation Wave suffer from the problem of the over-powered nature of Thor and Captain Marvel.
As for Galactus, as a part of the universe, any battle would end in a stalemate (though that may actually make for an interesting twist on the usual superhero formula).
It has already been confirmed that there will be another Avengers movie, it's just that finding an Avengers-level threat will be the issue.