Sideloading is fundamental to Android and it is not going away. Our new developer identity requirements are designed to protect users and developers from bad actors, not to limit choice. We want to make sure that if you download an app, it’s truly from the developer it claims to be published from, regardless of where you get the app. Verified developers will have the same freedom to distribute their apps directly to users through sideloading or through any app store they prefer.
Google
via Android Developers Blog