Plenty of people still have land lines
There are still people who don't want to stuff a tiny phone against their ears or worry about how many minutes they have left... alarm systems... work lines for telecommuters...
Anyway, AT&T was already doing something like this. For at least the last year or two we were forced to pick a long distance plan, and the cheapest had been bumped up to a $1 minimum. We've been using Google Voice for long distance and haven't dialed anything outside our area code in a long time.