While I'd love for Brooklyn to have its own MLB team again, I just don't see it happening.
In fact, when I came up with a
four-league alignment for MLB based on baseball history (which in turn was a modified version of another plan floated on this site), the AL and NL would consist of all the cities where they had teams in during the 1957 season (with every market that had at least one team in the 20th century at some point up to that point in the two leagues), with one exception - the second NL team in NYC is replaced with the Miami Marlins, who were a class AAA team in the International League in 1957, because territorial restrictions likely would bar another team from being established in NYC or a market which formerly had two teams but now only has one. If a third team does come to New York state, it will likely be in Buffalo.