Being an experienced person in dealing with streams of all sorts, streaming stuff myself sometimes, being a part of streaming communities,), being a bit of an expert in general on this stuff, it would never work.
1. Coli interests are too varied to end up creating something tight and to the point. Consider the fact that for NBA all the big games are shown on national TV anyway (counting ESPN as a part of this), there'd be no point. Then add in small groups here and there, you'd have to stream everything. That brings me to my next point.
Then these people dont have to partake. For me myself, I dont have a television. Havent had one in about a year and a half. If I want to watch sporting events I usually meet up with homies at bars, or I find some low quality stream online.
I would love some type of HD sports stream...even if it is only these nationally televised games.
Also, a lotta people aint paying for cable and ESPN so I think they would be interested as well. Plus not everyone lives in the US so these nationally televised games might not be televised at all in their nation.
But I do agree with your point about the amount of effort involved. We would just need to find a couple people with enough bandwidth and the correct kinda computer/tv setup.