According to wrestling attorney Mike Dockins, new TKO contracts have terms that say they have the right to match a contract with departing talent 6 months AFTER the contract ends.
They don't really want to pay AEW money for anyone but the big stars, and those people likely aren't leaving WWE to begin with. So I'm not really sure what effect it will actually end up having.
With them in private equity mode, it wouldn't make much sense on the financial ledgers for them to make a big money offer to someone like Ricochet and Ciampa, who they rarely ever pushed as anything but middling midcarders, just to keep them from going to AEW.