The end credits scene for Ant-Man and the Wasp, released over the summer, saw Scott Lang stuck in the Quantum Realm after his nearest and dearest were killed off by Thanos’s Snap from Infinity War.
But will it play a crucial role in the Marvel heroes overturning the Snap and bringing multiple superheroes back to life?
Speaking in the book Marvel Studios: The First 10 Years, Feige said: “At the end of Ant-Man we followed Scott Lang into the Quantum Realm for the first time.
“We were beginning to peel back the onion that would later be completely peeled back in Doctor Strange as we go into the multiverse. So that was our little test into that.”
He added: “But now the Quantum Realm is a whole other territory that we can play with to tell our stories.
“This Quantum Realm is much larger than we ever imagined, and there are all sorts of adventures to be had at that level, which perhaps we will explore in another film.”
Is Avengers 4 that other film? We will have to wait and see.
For now, a countdown clock has been launched on the movie’s official page on the Marvel site.
It comes as the wait for the movie’s official title and its trailer continues.
Previous alleged leaks suggesting it would be called Avengers: Annihilation have not been confirmed or debunked by the studio at this stage.
However the Thanos conundrum is resolved, there are other MCU adventures waiting in the wings.
For one, Spider-Man: Far From Home has already finished filming – with Tom Holland back as Peter Parker.
Parker was, as fans will know, one of the fatalities of the Snap in Infinity War – so how he comes to be fighting fit for a whole new movie remains to be seen.
The actors are certainly not giving anything away – asked if he’s in Avengers 4 by Jimmy Fallon, Benedict Cumberbatch (Doctor Strange) said simply: “I’m dust, baby.
“I’m just out there. I’m in the ether. I’m probably part of your food chain. I’m in your stomach somewhere.”
Avengers 4 is out on April 26 in the UK and May 3 in the US.