One way to make this ugly real fast is for content providers like Netflix/Amazon to completely block subscribers from ISPs that apply QoS to negatively impact them. Say something like "we can't provide a great experience so we think you should have no experience at all because it wouldn't be fair with us and with you. we are sorry." and make it explicit that it's because of the ISP they are using. The ISP think they…
So your expectation is that if Netflix intentionally prevents users from using their service because they don't like the user's choice of ISP, that will turn out well for Netflix?
The whole net neutrality discussion is a power play between content providers and fiber owners, nothing else. The discussion about freedom and competition is awesome (and right!), but at the end it's these two huge groups fighting each other while we are screaming "think of the children!".
What Netflix would be losing if a subset of their customers on provider X is already getting crappy service and it can't do anything about that? At some point they will have to decide what to do about all those complaints and refund requests.