They also need to play fewer games. The Cubs' star Anthony Rizzo said he would gladly take a pay cut. Teams play 162 games a year. That's just insane considering how demanding the sport is and how frequently players get injured.
I don't think they need to. Baseball's been run this way for decades, and people are only now complaining about the number of games per season.
One part of the entire draw of baseball is that (usually) it's looked at more-so as a marathon of a sport. It's all about which teams can withstand the long season than not. You could have a 10 game win streak in May, but that doesn't make a difference in September if your team's division is still close. You need to have the health at that point and durability of players to continue to be successful, especially through the playoffs.
I would think it'd only work if everyone in the game was willing to take x% off their revenue. If you take out 10% of the games, the revenue would fall off.
If the schedule is reduced, a certain amount of payback or retroactive contract negotiation would have to occur with the myriad of networks paying to broadcast the games.
