All hopes for the appeal seem to hinge on the idea that the CAT will determine cloud gaming to not be a separate market. Well, it is. And even if it wasn't, the CMA has enough discretion with their market definitions that they can class it to be one.
South Korea agrees, and barring one EU official's comments outside of their published decision, I don't see where the EU denies the distinction, either. Speaking of comity, EU failed to take this into consideration when approving the deal, knowing the FTC and UK were against it.