Given that Android took off better than anticipated, this would be rather risky move for global Android adoption. Carriers still "own" customer contact in most countries. If they decide to be really afraid of Google, they will stop helping Android adoption.
In early 00s, Nokia wasn't that operator friendly compared to other OEMs. This led to situation that operators took less (or didn't take any) Nokia phones to their subsidised selection. This was the main reason for Nokia's bad performance in US.
Then Nokia started licking some juicy carrier butt. Boy it was a shitty time to work in Nokia. Requirement pipe line was filled with all kinds of crazy useless requirements from carriers, and that essentially halted the software development.