Define length... 4/1 - 11/1 ... 7 months or 162 games?
Took a look at one team ... just to get an idea.
In 1955 there were 154 games...regular season went from 4/13 - 9/25 and there were less playoffs... done by 10/15.
In 1970 there were 162 games ... season was done by 9/30.
2017 season did not end till 10/1.
The issue - I think - is that in 1950 there were 22 double headers. in 2017 3.
TV revenue is too great not to have as many games as possible in prime time.
Either way you cut it ... by days or by games ... there will be lost revenue.
The only way a season will get shorter is if the players hold out in collective bargaining and are willing to give up salary. At 51 I have a better chance of playing for the Yankees than any of that ever happening.