I'd say Iceman since he isn't doing anything and us an Omega level Mutant then
X-Men Forever
It's probably Namor. I doubt it's any X-Men related characters.
I don’t see why they would hype it up as a special announcement if it was Namor. He was with the avengers as recently as Jason Aaron’s run.
I'm thinking Iceman or Synch, with the latter being more likely IMO.
https://twitter.com/Marvel/status/1790064482263200216
"Stay tuned this week for more announcements, plus, find out which X-Man will be joining Earth's Mightiest Heroes in 'Avengers #17'."
"Danielle... I intend to do something rash and violent." - Betsy Braddock
Krakoa, Arakko, and Otherworld forever!
Almost anything I can come up with is easy to come up with a reason why it would not be, so I am just going dream and say Hope Summers. Something big happens to her in a couple days and I would like there to be new chapter for her with a new mission.
My hopes are for Iceman, Synch or Dani.
"I AM A GODDESS OF LIFE AS WELL AS OF STORMS. IF IT IS WITHIN MY POWER TO SAVE YOU -- I SHALL." - ORORO MUNROE
Mighty? Colossus should be an Avenger for a change. Though, he might be so out of place there. I bet Polaris has a chance or maybe Firestar will return as an Avenger.
Peerless and Fearless
Colossus doesn’t really add much in terms of powers to the current Avengers team.