Fortnite for Android is coming (eventually), but when it does, you won't be able to find it on the Google Play Store. Instead, Epic (the developer of the game) will distribute the APK on their own website in an effort to both re-establish a direct relationship with gamers and retain more revenue.
https://www.notebookcheck.net/Fortnite-s-Android-port-won-t-be-available-in-the-Google-Play-Store.320776.0.html
So, they are OK with Apple taking a 30% cut on iOS, but not with Google doing the same on Android? I don't get it.
Would the user have to keep downloading APKs in the future for new updates of the app?
They will be distributing an installer that will be downloading and updating the actual Fortnite app, so you'll only need to download an .apk manually once.
They are not so much okay with 30% on iOS as they have to live with it because Apple controls every distribution method and can just pull their developer license if they abuse sideloading.
This is great! Now more users will enable sideloading and break Google's monopoly!