Yes and it is worrying. Google ought to make everything AOSP and but keep anything proprietary. They have nothing to lose so I don't understand why they are stripping stuff from AOSP.
With so many OEM's running to get Google Play services I don't think there's any risk they would lose that.
Anyone wanting to make their own phone without Google services is going to have a hard time selling that phone.
Mostly it's only the 3rd party ROM's that use it the most, and they are a tiny niche.