Avengers: Infinity War - 9 Ways It Sets Up Ant-Man And The Wasp, Captain Marvel & Avengers 4
3. The Dead Heroes Need To Come Back
The ending of Infinity War is brutal, with heroes dropping like flies before turning into ash, but it cannot stick. Although there should be consequences from what happened and the heroes need to deal with the fact they died, they undoubtedly need to return. It's a simple business decision, necessitated by star contracts and already confirmed sequels.
Spider-Man has a Homecoming sequel coming out just after Avengers 4, Guardians of the Galaxy Vol. 3 follows a year later, and the billion-dollar box-office guarantees Black Panther 2 will happen sooner rather than later.
It may not entirely go down as expected, and some of the fallen heroes could stay dead (though it's really just Nick Fury and Maria Hill who don't have an obvious future), but for the most part we know a lot of Avengers 4 is going to have to be centred on bringing these characters back to life.