Ehhhhhh, not sure I buy that. Sure, giving one person 4 streams instead of 1 has very little marginal cost, but giving everyone 4 streams instead of 1 is not cheap. They need more servers to serve the extra traffic, and they still have to pay for data transfer, presumably, even in places where they've put PoPs inside ISP data centers.

(Granted not everyone will be using those 4 simultaneous streams all at once, and some people won't even use the extra streams at all, but I'm sure enough will that it won't be free for Netflix to provide it.)