There was rumoed to be talk of a new league in 1996 if the strike/lockout kept going. That's the first place I'd look. MLB uses the strikebreakers, Cal Ripken Jr. is enticed to play for a rival league and keep his sterak going (while Baltimore chooses not to play so as to keep his consecutive games int he majors streak active.) A very hastily set up 6 team league plays 150 games, it expands to 12 the next year as teams contract in MLB, maybe by 2000 the leagues are playing each other in a true World Series.
Problem is, of course, would baseball survive that?With all that carnage it might have problems keeping players on such high salaries, but maybe.
Perhaps it needs done when baseball is still widely popular - was anyone loony enough (okay, besides Charlie Finley) to even conceive of replacement players in 1972?