Something like 13% of comcasts outgoing data is bittorrent already. The issue is most people won't like the idea of having their upload bandwidth being without their knowledge or permission.
What Netflix neet do do is to use some smart protocol like utp and have sane limits by default to not saturate the uplink and make other services slow. If they manage to do that, then most users will be happy. Slap in there an on/off checkbox and a manual bandwidth limiter for the advanced users, and even most of those that know how p2p works will not complain.