I don’t feel great about this ruling. Whatever a “reasonable” fee is supposed to mean, Apple will interpret it to some ridiculous amount. Before the ban, they tried to charge 27%
It should be based on the app size, so maybe developers will stop shipping apps with a single feature and one button that takes 700 MB because of random bloated third-party SDKs that aren't even used.
Money makers on the AppStore are games, and games need assets in high definition. Third party SDKs are probably a drop in the bucket in comparison with visual assets.