The Ant-Man movies have largely functioned in its own little corner of the MCU, save for a quick appearance by Falcon and the Ant-Man and the Wasp’s mid-credits scene.
If this theory ends up being legit, it would be a bit shift in the MCU.
On top of giving Michael Douglas’ character a larger role in the greater shared universe, it would also make the Ant-Man franchise an essential part of the overarching narrative.
But with so many heroes having faded to dust thanks to the power of the Infinity Stones, the Avengers are going to need all the help they can get, with Ant-Man and Captain Marvel helping to fill out the ranks.