100 Mbps connections are becoming pretty cheap is some places. 30 euros a month here, no usage cap.
So yes, streaming a BD is definitely something I would consider streaming (in any direction) if there was a point to it. Because obviously it's easier to stream a rip of nearly equivalent quality (not a 720p one, please).
What I'd gladly have would be a streaming friendly P2P network. It always feels a waste to download a movie at 10 time its bitrate, yet not being able to watch it because of that tiny 128kb chunk missing in the first mb... And I'm pretty sure it's the same for whoever is benefiting of my upload.