mnmalst parent
In my opinion, the biggest problem that comes with this, is the fact that google play independent apps will become A LOT less popular. To a point where alternative roms are even less interesting to people which in return makes developing apps for them even less interesting.
Some people even sideload on iOS, which doesn't allow sideloading. They do this by getting an apple developer account, installing Xcode, compiling the apps themselves and refreshing them on their phones every week. And this seems about as popular as Android sideloading where you just download an app and install it...