No major league is going to forty(!?) teams any time in the next few decades, not even the NFL. Period. And this is especially an issue in baseball because of the automatic fact that any MLB expansion also necessitates four more minor league affiliates per team. So please stop the rambling fantasy booking for a bit and concentrate on the actual issues at hand.
MLB is likely to add two (and ONLY two!) teams to get to the same 32 number as the NFL and NHL. For those, three or four cities seem likely candidates.
The first is Montreal, as there's local support and a real understanding among baseball intellectuals as to how much the Expos really were mishandled by many decisions over the years beginning with having to play in the white elephant of Olympic Stadium up through Jeffrey Loria (who is a fraudster, to be frank). They deserve recompensation for the way the franchise was screwed over. There pretty much a shoe-in. The only real question is if they rejoin their old traditional rivals in the NL East or wind-up in a division with the city's NHL rivals of Toronto and Boston. Either one is appropriate, but I hope for the former because the revived Expos must have their first game against the Mets in Queens, just as the first and last games of the original Expos were against the Mets in Queens. (I went to the latter, and still have the scorecard/program.)
The second is Portland, which seems to have a solid plan and local support in play. Plus a desire to have them be a travel partner of Seattle; that is, a team on a road trip to Seattle would also play Portland on the same swing, reducing travel distances.
The third is Nashville, which is already a very strong AAA market, has significant local interest, had shown itself to be a very strong sports city (even for a sport no one would have expected to work, like hockey) and would be a good geographic rival for Atlanta. (Memphis is a non-starter, by the way. It's a smaller metro area, and much less affluent than the Nashville area. They have trouble with supporting just the Grizzlies, which are often seen as one of the most likely NBA teams to move.)
The fourth is the wild card of Vegas. No real rumors of much push for it, and they just (finally) opened a new ballpark for the AAA team after far too long to get it done, but brining in another major league sport (indeed, the one that gave the world the term "major league") would be seen as another feather in the cap of a city trying to get the world to take it seriously. And, bluntly, betting against the house in Vegas is literally the worst idea in the world. All it takes is the right person deciding to do it and, boom, Vegas is in Major League Baseball.
Of course, there's also the fact that neither the Rays nor the Athletics have made much progress with new ballparks. The A's announced their intention to build at Howard Terminal, but there's pushback about turning good quality dock worker jobs into low-paying stadium jobs. The backup is a new ballpark at the Coliseum site, which A's ownership has been seeking to buy for the purpose of redeveloping it and making money off the real estate. But who knows what the final outcome is there. Meanwhile, the Rays are still in the same boat of a lousy stadium that was outdated the second they started playing in a lousy location on the wrong side of the metro area. It's not that there's no fanbase (the local TV ratings are actually in the top half of the majors), it's just no one wants to actually trudge to the stadium. They need to be in Tampa. And probably will sooner than later. If I were a betting man, I'd actually say that the A's have a greater chance of moving to Portland than the Rays moving to either Nashville or Montreal, despite the rattling last year.
