While it would be more difficult, my vote in view of the tendency pointed out elsewhere on this page for twenty-team leagues to have too many All-Star teams, would be that we try to contract the leagues that have the most unowned teams by enticing the owners in those leagues into other 24-team existing leagues, using a reallocation draft.
This probably won't work because owners who have worked to build a team will be jusitfiably upset about losing that team, but perhaps some leagues could volunteer for contraction based on a majority vote and other leagues could volunteer for a reallocation draft.
Dave N