I don't think that will happen anytime soon. There are too many cities that want a team in both leagues, for the fact that they're an easy sell.
There are too many games in the baseball season, not to mention a lot of baseball games are played during working hours, so you won't see a lot of teams selling out series during the course of year.
Washington, DC is the only city really trying to get a baseball team, where as you have cities like Columbus, San Antonio, and LA, trying to get football.
Then you have St. Louis, Louisville, New Orleans, Anaheim, San Diego, Cincinnati, and few other cities trying to get basketball teams. I think if baseball had that kind of leverage, they wouldn't consider contracting.
Then there's a cap in both leagues, and not to mention there's revenue sharing amongst the owners in those league's as well.
The NBA & NFL, both have big contracts with several networks, where as baseball has ESPN, & Fox.
NICE