Oh I’m sure Epic is aware Apple will fight like a rabid dog. They were quick to kill Epic’s dev account, and point out that this could affect future Unreal versions. The Flash comparison to the status quo is good for understanding what Apple wants to do, but Unreal is so much more than Flash. Ue4 is the product of six years of post release refinement, plus however many years it took to build it. Throw in some extra experience for lessons learned from the prior versions. Even though there are other options for 3D such as Unity, Cry Engine, and Godot, none of them come close to what Ue4’s out of the box features. (Unity’s plugin land leaves it in a weird spot.) Secondly, Unreal Engine can be used to make console games. This is a huge audience Flash never had, that Ue4 isn’t endanger of losing.
Unreal being left out the Mac environment wouldn’t be great, but so many developers don’t publish Mac versions. (Source: I have a Mac, not being able to buy games I wanted because they don’t have a Mac build is a pain. Many games were also left to be sad after Apple dropped 32 bit support for Mac. Heck so many of Epic’s free game giveaways weren’t made to work on a Mac. Point is so many developers don’t build for Mac. )