Why not everyone go buy a Nexus 5? It looks open as phones go, you can just root it with adb[0]. As long as you can root the phone and swap in your own OS I think Google's phone is as good as any other.

[0] http://wiki.cyanogenmod.org/w/Install_CM_for_hammerhead

Edit: I didn't read your post carefully enough. Yes, it would be wise to assume that Google will eventually become malicious and try to future-proof by supporting entities making comparably liberated phones.