I understand everyone wants to dump on Google here, but Nest labs is the company that made the API, not Google, and AFAIK they never turned a profit. So as far as "promises" go, Google didn't really make a promise to anyone w.r.t the API FWICT. Google has shuttered their own products plenty, but when you purchase a loss-making company you're going to want to streamline everything, so you can make your money back.