At the time of his final match (so far), CM Punk was still regarded as one of the most technically proficient and charismatic wrestlers in the business.
Of course, we don’t know anything for sure yet, so we’ll just have to wait and see what happens.
I think a signing would immediately put more eyes on AEW as an organization in a way that Hulk Hogan’s defection to WCW did back in the day.
It would stand to reason that he’s still that guy, and even if he’s not quite that guy after his UFC debacle, people in 2021 are still chanting Punk’s name during wrestling matches that he clearly has no involvement in.