So with 2 new teams coming in next year, the league will be at 24, and they're looking to expand even more, right? If they get up to 28-30 teams eventually, I think it'd be cool to see them treat the two conferences as essentially two different "leagues".
So there's currently 34 games on the schedule, if you had 15 teams in each conference, you could play each team in the conference home and away, which is 28 games. Then the remaining 6 could be a rotating system where you play 6 teams from the other conference every year, just for some variety.
I don't know if that sort of system is viable for the MLS, but I like the idea of being able to play all the teams in your conference home and away, as the league expands even more.