"...All of the major sports offer streaming of pretty much every game a fan of a specific sport could want..."
Only they don't. If you think about it...
whenever you want to stream from the web... you generally have to enter your TV provider credentials. So if you don't have cable, you can't stream a lot of those games.
I have cable and subscribe to MLB.tv and they still blackout games because (I think) some local station bought exclusive broadcast rights.
MLB.tv is interesting because they generally don't have commercials. Oddly, I wish they did. When the broadcast pauses for commercials, my screen basically goes blank and the TV gets silent. I wish they would just switch to a whole stadium camera with crowd noise.
Localized networks like the various Regional Sports Networks, Fox Sports (insert City or State Name Here), Big Ten Network and Pac12 Network are stealing the casual fans of specific teams. All of the major sports offer streaming of pretty much every game a fan of a specific sport could want.
It's telling that the first new program ESPN added following the layoffs was a simulcast of MLB's Intentional Talk. Yet another talking heads show with a TMZ bent. I don't see this ending well for them.