In 2013 the Houston Astros are expected to move to the American League. This has Major League Baseball looking to adjust its interleague schedule. Unfortunately this could end or atleast limit the home-and-home series between natural rivals which for the Mets and Yankees is currently a six-game series, three games at Citi Field and three games at Yankee Stadium.
According to sources, the 2013 Major League Baseball schedule is still being discussed and nothing has been finalized.
The Mets and Yankees have played three games in both the Bronx and Queens every season since 1999, the year before they squared off in the first true Subway World Series since the 1956 World Series which saw the New York Yankees defeat the Brooklyn Dodgers by a score of 4-3. The teams will continue to play six games a season every three years when the AL East and NL East line up for long-form interleague play. Since interleague play began in 1997, the Yankees lead the series against the Mets, 49-35.
One potential option would be to have natural rivals such as the Yankees and Mets play a four-game split series each season, two at each teams home ballpark.