We wish you luck, but if it breaks, dont come crying to us over it.
The history of mobile operating systems shows that your preferred strategy is a losing strategy. Users DO come crying over it, and developers cry twice as much. J2ME was basically Android 0.1 and took this approach - it was just a bunch of API specs and then phone vendors could license different implementations, write their own, etc.
J2ME sucked. I know this because I tried to write apps for it. Literally every freaking phone had its own unique combination of stupid, obvious bugs that rendered key APIs unusable without enormous piles of hacks. J2ME developers theoretically wrote Java, but often used a C style macro preprocessor because so many hacks required different source code to handle.
Android learned from J2ME and took a different approach - one single reference implementation that everyone builds off and is not pluggable except in very small, tightly controlled ways. You can modify the reference implementation to your hearts content unless you want access to the Play Store, in which case you have to pass the "Compatibility Test Suite" for core OS functionality, and for some other kinds of things that are impossible to unit test (e.g. Maps quality), agree to ship the Google implementation. This saves developers from J2ME hell making users and developers happy, and still lets manufacturers tweak things that aren't covered by the CTS, like reskinning things.
I see no evidence the EU has any understanding of the delicate balancing act Android represents, or the history of mobile phone operating systems. I fear this will be yet another bull-in-china-shop scenario. On the other hand, if Google are doing things like what Microsoft used to do by saying "if you sell any Google-services phone you cannot sell any non-Google-services phone" then that'd be a problem that is correctable without hurting developers.