Well at this point there's only one higher court they could go to (if they'd even take up the case). Frankly the case law on this subject is pretty well established and the judges have just been following existing precedent.
Epic failed spectacularly. They couldn't prove a monopoly, and even if they could, they were not able to point to any instance where Apple abused a monopoly position to turn the screws on customers or developers.
M00x, you mentioned you know folks at Epic that are working on WebGPU. Do you mind sharing who they are? Because last time our team spoke with Epic, they mentioned they are not working on this (our company is a startup from Canada building tools and a platform-as-a-service to enable developers to bring their games to the web, and a large focus of our work has been building out a WebGPU backend and integration for Unreal Engine 5).
The judge makes a decision on their interpretation of the case and the law. This is a very important distinction in decisions.