I've been thinking about this forever. Well, ever since Twitch became a thing.
We would simulcast audio reacting to the game - not doing play-by-play. We wouldn't cast video of the game, obviously. Our video feed would be us and someone's PC so they can pull up Fangraphs or whatever. The intent would be for people to have the game on but muted on their TV, and then they'd have our audio and a second screen experience. It would be the absolute tits.