I never knew about F-Droid. A FOSS Android repository is a great thing to have.This is a dick move by Google, protecting their own interests at the expense of their users. Still, Android being Android, it's easy enough to sideload ad blockers anyway. AdBlock Plus for Android is already adapting to this and AdAway has simply instructed its users to use an alternate open market called F-Droid which lets you directly download the APK.
Thanks!