If the Dodgers or Giants don't move to Cali then the Braves move to LA in 53 and the A's go to "The City". Boston and Phillidelphia simply can't support two major league teams
Err, why? The Braves moved to Milwaukee in 1953 while the Dodgers and Giants moved in 1958.
Truth is baseball will eventually make it west, and the PCL will be this timelines equivalent to the Continental League. It is also likely we will see something like the Kansas City A's move to LA, and the Washington Senators move to San Francisco, then MLB will expand to DC and KC to replace those departed teams, then the NL will expand probably to Houston and Atlanta all the while licking its chops waiting to get into the West Coast Market. Now you could very well see the Braves going to say Seattle and be the only NL team on the coast for a few years, its also a very strong possibility the Cleveland Indians move to Seattle (it nearly happened in OTL) in the mid 1960's, the NL will probably look into LA and Oakland for an early 1970s expansion, while the AL looks at San Diego, and possibly Seattle