That's true, but expenses for MLB teams have also been skyrocketing. I suspect if you took all the revenue streams, subtracted all the costs teams incur except player payroll, then split the remainder 50/50, player payroll would go down considerably. It's also likely that the move to online streaming will significantly drop the value of some of the TV contracts that have been propping the league up.
If MLB really wants to throw the union a cookie though, they should let individual players use and keep 100% of the profit for the advertising patch on their uniforms. Maybe let them do the same with socks and shoes or something too.