Fortnite notwithstanding, Epic also makes the Unreal Engine, which is one of the biggest ones alongside Unity -- especially for cross-platform games. Hindering iOS development of UE will affect a lot of other game devs, both huge and indie.
"(2) a declaration that (i) Apple's termination of the DPLA and the related agreements between Epic Games and Apple was valid, lawful, and enforceable, and (ii) Apple has the contractual right to terminate its DPLA with any or all of Epic Games' wholly owned subsidiaries, affiliates, and/or other entities under Epic Games' control at any time and at Apple's sole discretion."
It's a loss for cross-platform gaming altogether. Apple just really doesn't give a damn about their users =/