I can think of a zillion loopholes by which this will be evaded.
Is there a definition of what is THE internet? surely comcast can create a parallel construction and sell however they wish like a private toll road. It could have discrete points where it could tap into the "real" internet. Thus amazon or netflix or whomever could connect into this autobahn on the goes-into side and pop out into "the" internet at some Comcast hub in the customers town.
Picture it like FED Ex, transporting a package 90% of the way, then mailing it. the postoffice might not charge differently for different customers and Fed Ex might not either (or they could) but only customers with valuable deliveries would be willing to pay the cost of the combined service, which would be dominated by the Fed Ex high speed service.
That's effectively what companies like Akamai sell already and those are not part of the discussion of Net Neutrality.
It might be easy to regulate comcast if comcast is the parent company of both halves of this real and shadow internet. But if these services are split into two companies then what? Even if the shadow company is privately held by comcast this is going to be hard to regulate.
Eventually the shadow compaines won't even bother with their own hardware. They will lease a certain number of dedicated switches from Comcast for their own uses. these will be cut out of the real internet.
An alternative way around this is by selectively enforcing the tragedy of the commons. In principle Netflix could prioritize its packets on a neutral interenet by emitting 100 times as many packets where each packet is sent 100 times. the receiver ignores all but the first one of the redundant packets. This of course would be retaliated by others now squeezed out doing the same thing resulting in 100x the traffic for the same data and no gain for anyone. COmcast would come down hard on these miscreants but would it be selective?