but it's very unlikely this will happen.
No, it will. Comcast pushes for this legislature because they want to use it. Otherwise they don't push. They push with lobbying and lawyers, both are expensive.
I. Why? Easy. Because it will be literally the worst business decision in history. They would basically end up going to war with companies like Microsoft, and people will simply find shortcuts to avoid paying fees, so they would actually loose money.
Haven't you heard the story of netflix? They won't just half the speed from one day to another. They will slowly throttle the connection and go to netflix with: "hey you know, it would be a real shame if something happened to your Internet connection"
That has happened. It will happen again. It is internet protection money.
And honesty, netflix is fine, youtube is fine, Blizzard is fine and most other established companies. They have the spare change to negotiate. But what won't be fine are the new guys. What you won't see is big multiplayer games from new companies. League of Legends would not happen in the new environment.
I am not worried about steam, I am worried about gog.com and humblebundle. They will still work, but may be too slow to be competitive.
And circumventing it? How? They not only control your connection, but also theirs. VPNs don't help in that scenario. And you can be sure if they throttle every package they don't recognise. I am sure it already happenwd with TOR.