Of course if someone does manage to set a precedent that including copyrighted works in AI training data without an explicit license to do so, GitHub Copilot would be screwed and at best have to start over with a blank slate if they can't be grandfathered. But this would affect almost all products based on the recent advancements in AI and they're backed by fairly large companies (after all, GitHub is owned by Microsoft and a lot of the other AI stuff traces back to Alphabet and there are a lot of startups funded by huge and influential VC companies). Given the US's history of business-friendly legislation, I doubt we'll see copyright laws being enforced against training data unless someone upsets Disney.