Charging very different users the same is obviously not as efficient as tiered services - otherwise there would no such thing as tiered service, anywhere. By forcing them not to use a legitimate business model you are telling them that they may not recover costs as efficiently.
They already charge different users differently -- I pay more money for a faster connection since I use Netflix heavily. If I didn't watch streaming video, instead of a 25mbit connection, I'd buy their cheap 6mbit connection (or would use an ADSL provider). If they find charging for bandwidth alone to be unsustainable, then they can charge for data too -- charge $20 for each 100GB, or whatever covers their costs. They have lots of flexibility in their pricing structure. They can add peak surcharges or whatever else they need to do to pay for their network.
The type of business that will be more likely to fail in this situation is the start-up or the small scale business.
How can a startup expect to charge money to large users like Netflix, Amazon, etc? If Joe's House of Internet tried to force Netflix to pay up, Netflix would tell them to shove off and wouldn't worry about losing a few customers. But when Comcast (with over 15 million internet customers) tells them to pay up, they have little choice, since they can't afford to lose millions of customers.
Sure, allow more competition. I'm all for a freer market.
But don't reduce competition by telling Comcast that they can't incur costs on Netflix, when Netflix is incurring costs on Comcast.
Netflix isn't incurring costs on Comcast, I (as a Comcast customer) am incurring the cost by requesting the data from Netflix, so I should be paying for that -- Netflix isn't forcing me to accept their data, I am requesting it.
Why is it worse to have hidden costs in your monopoly bill than your more competitive Netflix bill?
Because, it's a hidden cost and I can't see the true cost of my Comcast connection. If I pay $50/month to Comcast, and have a hidden $5 for Netflix, $3 for Amazon, $5 for Youtube, $1 for Facebook, etc, the true cost of my bill might really be over $100, and if I knew that, I might find another ISP more cost effective. And more importantly, if Comcast charged their true cost of delivering service and that ended up being $100/month, that might be a level that makes it profitable for another provider to come in, while if the content provider subsidies kept Comcast rates artificially low, then there would be less incentive for a competitor to enter the market since he wouldn't get the same subsidies yet he'd be competing against Comcast's subsidized rates.