I think it'll come from two directions:
1. MLB needs to constantly replenish its fan base. Young people stream, most of my generation and below doesn't even bother with cable. If you can't stream, they don't bother watching it. MLB will have to adapt its model to the iTunes model - otherwise it will be a victim to the next Napster or its fan base will dwindle. Media is changing - youth would just as much assume watching the highlights than the full game. The talent pool they are drawing from has already shrunk with kids moving to more entertaining sports/
2. Teams are hoarding cash and franchise value. Young players have to recognize they are all vastly underpaid in relation to the revenue and value they produce. When Mike Napoli, of 30+ HR and 100+ RBI and a critical role on a World Series team can only get a one year $8.5m deal at the end of free agency, young players are going to wake up to the fact they they need to make their money earlier in their careers. MLB teams have stacked the deck against them cashing in after arbitration - except for the elite few.