This might actually mean more development of the AOSP suite of apps. AOSP already offers a mail client that looks and feels just like the Gmail app, the Android system needs WebView in order to work and that's Chromium-based, so OEMs can just grab the same Blink version as Chrome Stable and buil (though I'd prefer if they use Firefox instead), the AOSP keyboard offers all of the Gboard's features except for all the creepy spying and the gesture typing, apps like Google Play Music and Photos have AOSP replacements, but they haven't been updated in years.
The issue will be if they decide to include Google Play Services in this. Without it most of the apps break one way or another, thus it would force OEMs to pay upfront.
Sure, there's MicroG but it's an alpha and it breaks every time Google pushes an update to Google Play Services. And no OEM will never attempt to make a GSP replacement just for the EU.
There's also SafetyNet which is used by many popular apps (including Snapchat, Pokémon GO and most of the bank apps) and it won't let those apps run without Services.
In other words OEMs would be forced to pay in order to offer useable phones.