I'll believe it when I see it, personally.
Whilst I still read news on the daily, and the odd clips, I haven't properly watched WWE in 3 years (did watch RAW for the first time since April 2018 this week, however - shocker), nor AEW in about a year - so I wouldn't have a clue where he'd fit. I doubt he'd return to the 'E unless presented with promises on a contract (which is gonna be a no-no for them), as well as a massive payday. Aside from Roman or Lashley (I'll give WWE credit there - the Roman 'Head of the Table' gimmick with Heyman has been amazing of what I've checked out/seen, and Lashley has been handled how he should've been handled for years), there's no one I really want to see him face.
AEW on the otherhand just has enough talent as it is. Then again, I'm not a CM Punk fan - so, I'm pretty bias. In all honesty, he's on Bret levels for me - so, thanks, but no thanks. If he returns, I'll probably check the clip, but that's about it for me, brother. However, if he brings in more viewers, more buys, and so on - then I cannot argue that it'd certainly be a good acquisition for them. Certainly would attract more eyeballs, even for the short term (then working to retain those viewers).