In theory there wouldn't be "one company" anywhere other than the wires. If you have a choice between ISP A who is deliberately congesting Netflix, ISP B who receives Netflix over uncongested transit, ISP C who was uncongested extortionate peering with Netflix, or ISP D who has uncongested free peering with Netflix then you just choose whichever ISP provides the price and performance that you prefer. And if all the customers choose ISP D, maybe the other ISPs will change their policies to try to win customers.
Unfortunately there are other problems (like "your DSL being down is not our fault") with unbundling.