It requires changing browsers, to let people distribute Google Hosted Apps on their own domains (as long as Google approves). Sites distributed in this way will get preferential treatment by Google.
This is essentially an App store model, similar to Google Play, and the really big danger is that we end up in a place where you either distribute (and host) your website through Google's AMP registry, or you're not actually on the web (in the same way that distributing your Android app as an APK outside of the Play store is not a realistic distribution channel).
I hope Firefox, Safari and Edge will resist this.