2. AEW Star Darby Allin
Darby Allin is a top star in AEW. Not only is he big with the AEW fans, but fellow AEW stars all seem to love him. After signing with AEW, Paul Wight said that if he could turn heel, he would love to wrestle Allin. When CM Punk made his long-awaited return to the ring, AEW booked him in a feud with Allin.
If Darby turned heel, it'd feel like one of the biggest betrayals in wrestling today. Darby is a dark character (in the visual sense) and the darkness adds a cerebral feeling to Black's heelish persona.
The turn practically writes itself. Sting is one of the most beloved personalities in wrestling. He has been by Darby's side ever since Sting arrived in AEW.
Having Darby turn on Sting would generate some serious heat with fans. Plus, if Sting wanted to formally retire from in-ring competition, what better person in AEW to retire the Icon Sting? It would take careful booking to make the turn work, but AEW has shown that they can book in a way where anything is possible.