Apple never cared about games (minus maybe a short period when the G4 came out), and gamedevs know it. Unreal was never a serious contender for iOS. So no serious immediate effect on either side.
In the long run, gamedevs would be even more reluctant to provide iOS/MacOS builds, which doesn't matter at all since people don't buy Macs for gaming.
Apple cares desperately about exclusivity since even before Cook. If Android has the same games and the same apps then there is less reason to favor iOS. There is nothing sacrificed to move between platforms. They don't care for any technology that fosters multi-platform games or apps.
Apple Arcade could basically be called "Games Never On Android".
> Here’s what being “exclusive to Apple Arcade” means. The game is a mobile-exclusive and cannot be released on other mobile operating systems ... Video game consoles are not considered mobile
They even banned Unity3d, Mono and the concept of 'cross compilers' while they were waging war on Flash, who at that point were perfecting cross-platform compiling from Flash "the IDE" to native Android and iOS apps.
> While the primary message is that there are Kindle apps on lots of devices, the secondary message [something garbled] is that it is easy to switch from iPhone to Android
Ah, wonderful. A platform where Apple can remove backward compatibility even more easily, and which forces you out of the other subscription services.
The big difference between games and other software, is that typical devs also profit from Apple making changes, e.g. Adobe managing to deprecate their previous licences and switch to subscription-only without backlash since it's Apple changing the platform. So Adobe loses a bit from porting, but gains more from new subscriptions.
Old games are almost never ported as is, at best they're "remade/remastered" which is a serious investment. So Apple making changes and choosing their own APIs is a pure loss for gamedevs. That's hardly the only problem but that's a big one.
In the long run, gamedevs would be even more reluctant to provide iOS/MacOS builds, which doesn't matter at all since people don't buy Macs for gaming.