Avengers: Endgame: 12 Post-Credits Scenes We Most Want To See

5. Avengers Versus X-Men

Sooner or later, we're getting mutants in the MCU and we will no doubt see a new iteration of the X-Men. According to common thinking, the X-Men will simply arrive in the established universe (seemingly without an origin), which would be the right approach given Marvel's expressed desire to avoid retreading the same ground repeatedly (as they avoided with Spider-Man: Homecoming).

So why not use the Infinity Saga's end as a means to open up the multiverse and drop the X-Men into the picture fully formed? They could be introduced initially as an invading threat - with someone at SHIELD tracking multiple new energy signatures and then a sequence establishing that the mutants have arrived.

Assuming there won't be anyone cast, it would need to be creatively done, but then Thanos appeared well before Josh Brolin was cast, so it's not like it's entirely unprecedented.