An unannounced MMORPG based on a Marvel IP is in the works at Dimensional Ink, the studio behind DC Universe Online and subsidiary of Daybreak Game Studio. The game's development will be led by Jack Emmert, who designed City of Heroes and who currently leads development on DCUO. The project is a long-term one, so don't expect to hear more until 2023 at the soonest.
The news that the game exists came via an investor presentation from Enad Global 7, the company that owns Daybreak. The presentation lists it as "Unannounced MMORPG" and says it's a "Marvel IP based massively multiplayer online game." Dimensional Ink is based in Austin, Texas, and currently runs DC Universe Online.
Daybreak has had a lot of success as a publisher of MMOs, especially the ones that have sustained an interested audience despite never rising to the top of the heap. They're the publisher of Lord of the Rings Online, which is getting a revamp to go along with Amazon's TV series. DC Universe Online is also scheduled to get an upgrade, with "a graphics upgrade and the largest expansion content to date" scheduled for 2023.
Dimensional Ink's website has a space for an unannounced project, but little else.