I do not think this will have any negative effect with domaining. It would take a lot to effect overall internet usage.
Companies such as AOL started off (here in the UK anyway) charging per minute. So you may have been charged £0.03 per minute (obviously the charge depended on time of day). This was in the form of dialling special numbers that were charged at a different rate than normal calls. You would be charged from your phone company as usual for these calls and the ISP would get a % of the call money. I was 1 of the 1st people in my area on broadband here in Dundee. I was cheaper to get broadband than to stay on dial up (I was average of £50 purely for internet time but a 512MB connection cost £45).
I would envisage broadband to be done in a different way. Most likely instead of time spent online you would be charged for how much you download like the mobile networks were (or some still are).
This is not necessarily a bad thing. Light users could find their bills decreasing while leachers would have increasing bills. Hopefully however they would not try to use a move to increase the average bill and hide behind the new pricing structure. Any ISP will tell you it is the minority that degrade the service for the many. Some people think that unlimited download means that they should download at full speed 24 hours a day. It does not take many people doing this to affect those around them.
