For better or worse, Google has always had a light touch approach to which apps are allowed on its Play Store. As long as they work (mostly) and aren't gaping security holes, they're fine, and Google leaves it up to the users to sort through and filter out worthwhile apps. That's not going to change, but Google is planning on tightening things up in the next few years in regards to what apps will be available.
The first major change will be in what API level developers can target with their apps. Starting in August 2018, all new apps will be required to target API level 26, which corresponds to Android 8.0. In November 2018, app updates will be required to target that API level. In 2019 and going forward, those requirements will advance, and all new apps and updates will be required to target the highest API level available within a year of the corresponding Android version's release.
So if we see Android 9.0 bring API level 30 in October 2019, all apps will need to target that API level by October 2020. Make sense? Of course, if your app isn't receiving any more updates you can pretty effectively ignore all of that, but if you ever need to push out an update you'll need to make some changes.
Also starting in August 2019, all new apps and updates will be required to have 64-bit binaries. They can still support 32-bit devices, but they'll need to support both or they won't be allowed on the Play Store. Google touts this as being a big performance improvement in addition to being more secure.
Lastly, Google will be adding security metadata to all apps on the Play Store early next year, although developers won't need to do anything for that change.
Overall these changes are laser-focused on improving app security, but we'll see the added benefit of better performance, too.
source: Google
