As mobile is eating the industry already anyways, this is already what's happening, and phones have adapted to show and restrict data usage, and it'd be nice if we had that much control at home too.
Ideally, the per usage rate you pay for Internet should both be much more granular than mobile ISPs use (by the MB would be nice), and so inconsequential that you don't need to worry about it as a daily aspect. (Nobody spends serious thought about the cost of turning on the light switch when they enter a room.)
Ideally, the per usage rate you pay for Internet should both be much more granular than mobile ISPs use (by the MB would be nice), and so inconsequential that you don't need to worry about it as a daily aspect. (Nobody spends serious thought about the cost of turning on the light switch when they enter a room.)