Well, if the past is any indication of the future...I don't think Google will sue. I mean, sure, Gmail, play store, etc are proprietary...and if Google doesn't want those apps allowed, I know there are alternatives.
Also, I'm quite sure Google would have said something about all the custom ROM's and flashable Gapps packages around the internet being dispersed.
But yeah, smaller companies like ZTE, Huawei (however you spell it), etc, could REALLY benefit from this sort of move for them. Not to say that those companies make bad HARDWARE, but their software leaves a lot to be desired...
It will be an interesting next few months, between this, Samsung's new OS, and Xiaomis MIUI coming stateside supposedly.