Although Epic appealed to SCOTUS, and SCOTUS rejected their appeal, which makes it seem like SCOTUS is unlikely to rule that app stores have to be open.
In general the judicial system's bizarre treatment of Apple baffles and somewhat infuriates me. If Google has to allow alternative app stores on Android due to monopoly power, and has to allow alternate billing options due to monopoly power, and yet is the smaller of the two in the U.S., how on Earth does the legal system continue to give a free pass to Apple doing the same thing while having more market power in the U.S. than Google? It's obscene and makes me deeply question the integrity of the judicial system in the U.S. as a whole.
Personally I think both Google and Apple should have to open up their app store system and billing systems more broadly, but it's pretty despicable for the judicial system to simply pick winners and losers like this.