I'm thinking 68/350-ish teams.

If football had that, then you would need a 24 team playoff.

I think that's too many, but it would be fun. I say 16 is just right. And start some relegation/promotion, keeping the total number of teams in Division 1 to about 96 (12 teams per conference * 8 conferences) and then all conference champs plus 4 at large.