This...there's no nice way to say this. This would piss me the hell off. I don't take what carriers do personally, but in this case, anybody can admit it would be insulting.
When verizon was switching over to tiered data, they made the point "buy this phone now to get locked in on unlimited data!". Get locked in for what? The assumption is this is a permanent thing and that's why so many people bought thunderbolts when they didn't give a damn about the phone.
If they do a switch a roo on this, there will be a ton of people that switch back to dumbphones. That's my prediction. I know it sounds crazy in this insanely connected world, but when people aren't free to do whatever they want and they have to conserve, alot will be asking "then what's the point of this". Unless they lower the data overages to something more managable, this could be very very bad.
Is there a lock you can put on your data caps? If you have a 2gb cap, can you make it so once you hit that cap, you can't use data for the rest of the cycle as to not incur overage charges?