Tony Khan owns 'The Elite' as well as all of their other intellectual properties like 'Superkick Party', 'Superkliq'.
Kenny Omega & the Young Bucks wouldn't be able to take their theme songs with them to WWE like Cody did. WWE wouldn't be able to play any footage of them from AEW/ROH to show the WWE Universe who these guys are.
Literally the only thing they'd have left is their YouTube show, which they'd have to rename. The best thing they can hope for is Triple H allows them to use Two Sweet hand gestures again.