Could they do it without alienating their hardware partners? No.
Does Android require the Google Play store or any other Google services or non-AOSP code? No. Many Android devices ship entirely without Google stuff, including no Google Play store.
Could they do it even if they didn't care about alienating their hardware partners? Yes, if they also intend on being fined into the ground by the US and EU.
Their hardware partners, the OEMs, is what makes Android suck for Android users. It doesn't have to suck: OnePlus doesn't, and Google's own Pixel series isn't bad either. Avoid Samsung like the plague, LG and HTC also have questionable practices wrt ROM sanity and long term support.
Google's gotten away with extremely anticompetitive requirements so far. I can't imagine it would be worse for them to mandate 5 years of software support, something that's very positive for consumers.
Could they do it without alienating their hardware partners? No.
Does Android require the Google Play store or any other Google services or non-AOSP code? No. Many Android devices ship entirely without Google stuff, including no Google Play store.
Could they do it even if they didn't care about alienating their hardware partners? Yes, if they also intend on being fined into the ground by the US and EU.
Their hardware partners, the OEMs, is what makes Android suck for Android users. It doesn't have to suck: OnePlus doesn't, and Google's own Pixel series isn't bad either. Avoid Samsung like the plague, LG and HTC also have questionable practices wrt ROM sanity and long term support.