If the cities would and could support a MLB team, I’d look for places that would fill in a geographical map. I don’t think we need more teams in the NE, SE or upper Midwest. I’d look to expand to Portland and Las Vegas (or SLC). But, again, these would have to have owners and a population to support this. Then I’d create 4 divisions of 8 teams. With that you could develop a playoff structure … maybe the top 2 or 4 from each division, and figure it out from there. Universal DH would mean no inter league play. Divisions would look something like this.
West: Seattle, Portland, Oakland, San Francisco, dodgers, angels, San Diego, Phoenix
central west: Las Vegas (or SLC), Houston, Arlington, St. Louis, KC, Minnesota, colorado, Milwaukee
central East: cubs, ChiSox, Detroit, Toronto, Cleveland, Cincinnati, Pittsburg, Philly
east: Boston, Mets, Yankees, DC, Baltimore, Atlanta, Miami, Tampa
Edit to add … but before this, baseball needs to solve some of its other more pressing concerns first