I dont think it will end the same as in basketball, even if they both have a similar system. Basketball is straight into the pros with large contracts and whatnot. Baseball will always have its minor league system so we won't have large contracts straight.
Baseball I don't think will get rid of the 5-6 year control system, all a salary cap/max contract will do is keep contracts from getting too out of hand.
Also for me, I would implement a minimum cap as well. So teams cannot spend over lets say 150, but then they have to spend at least 100 mil, if they don't then players get paid extra money per game suited via the percentage under equally.
So a quick one would be, lets say they are 10 under at 90 mil, then each player on the 25 man roster will get like 2.4k per game on the 25 man roster so by the end of the season the team pays out 100 mil.
There is a lot of different ways we could do this, but getting something more equal to all teams to have the ability to sign players in theory is why anyone suggests a hard cap. We don't want only a few teams just signing all the best players.