I don't think I have to tell you all how shitty this would be, but it's not a "broken" Internet. We can sit here and concoct all kinds of worst-case scenarios, but we could also do that with anything. Your babysitter could feed your kid a bottle of aspirin - this is within the realm of physical possibility, just as it's within the realm of physical possibility that Comcast starts shaking down websites.
And before anyone even brings it up, Netflix and Comcast's peering agreement has nothing to do with net neutrality. Without peering, Netflix's path to consumers was long. With peering, it's not, which leads to faster speeds. That's it. Peering agreements have existed for many years, and will need to continue to exist for the Internet to continue to exist. It'd be much worse for the Internet to abolish all peering agreements in the name of neutrality (wtf?) than it would be for the FCC to have no teeth in enforcing net neutrality.