From the recent notes I made on the Google Voice and how it uses the carrier minutes and data to operate, it should be free in 2012 and beyond.
Why? Currently, Google Voice is not a VOIP service and it uses the carrier minutes and data to operate which means to make or receive calls the subscriber has to pay the carrier. See the image in that post. If Google Voice doesn’t offer VOIP service and starts charging for the voice calls, the subscriber will be double charged. For every call made or received, the subscriber has to pay to use Google Voice and then, since Google Voice uses the carrier minutes, has to pay the carrier for using the minutes. If this is exactly how it works, it will be very difficult to justify Google Voice. I’d definitely drop Google Voice and, I think, many other will do too.
Charging for Google Voice makes sense if either Google Voice offers VOIP services (like Skype which uses just data) or if it charges on a monthly basis - an amount for using their services. The free text messages and the call management service are worth paying for, but if it’s too pricey, one would rather pay the carrier and get rid of the call management service. Many plans offer unlimited text messaging and the call management service isn’t something that one can’t live without. Lo and behold, the biggest benefit would be that you won’t be providing any more self-data to Google than you already have or are!
There are some apps (Talkatone, GrooVe IP etc.) which use VOIP services like Google Talk along with Google Voice and allow for free calls over data. What happens if Google decides to get rid of the free calling service in 2012? Even these third party application will not be able to make free calls. The applications will use only data (and save carrier minutes), but Google Voice will not be free. It will be interesting to see what direction those third party applications take at that time.
All this will just be opinions/guesses/rumors, until Google comes out and announces their plan, which should happen not too far from now.