The good thing about google voice is that when it is finally axed, the US laws require them to give a way to port numbers. That's the only reason why I was comfortable using their service
You can initiate the request from the other side (the new carrier), in which case it is forcefully wrested in a day. If google still refuses, you can complain to the FCC.
As for google penalties for holding your number hostage, given that the business is dying there's really nothing other than an FCC lawsuit (which, as you imagine, would be for a paltry sum)
Do you mean until they start charging for it? They've been saying for a number of years that "next year" it will no longer be free. But I have not heard they plan to sunset the service altogether.
I still don't know why that's supposed to scare me. As long as they don't purge the contents of my Gmail and give me three months notice on closing products that I can export my data from... then, I'll find a way.
If I have my way, sooner or later it will be more convenient to just run your own Google Voice clone on Twilio, Tropo, etc.