I think Sunfire will be an Avenger soon.
'You can see here there still a lot of spots left to fill.
There are a few reasons why Sunfire makes sense.
- He is a mutant and the Avenger want to work with more Mutants
- He is Japanese and the writers said they wanted the team to have a lot of ethnic diversity
- And he's one of Marvel's older characters.
But the big reason is this.
Why else would he be on this cover if not for him joining the Avenger and It's really unlikely that.he will be joining the X-Men because none of the other X-Men are on this cover except Beast and Wolverine who are Avengers.