According to Brick_clicker, in a new podcast they've revealed that two new rumored sub-themes of LEGO Marvel will be coming in 2022, and will feature comic-based sets relating to Marvel Avengers. They've also mentioned that four of the sets will be in the Juniors (4+) range, and may be a new off-shoot from LEGO Marvel as well, similar to the most recent LEGO Disney Mickey & Friends Juniors sub-theme that released this past June.
There were no pertinent details such as set number, cost, piece-count, or availability, but the sets are expected to release early to mid-2022. There were also rumors of a Doctor Strange set coming in January, along with a new LEGO Spider-man 18+ set, which may be a Spiderman bust of one of the new suits from Spiderman: No Way Home. The Spiderman bust makes the most sense considering that 2021 brought us two of Spiderman's greatest foes in bust form—LEGO Marvel Carnage (76199) and LEGO Marvel Venom (76187).
As always, these are only rumors and should be treated as such. We'll be reporting more details on the new sub-theme as the information is made available.