The final game in the series was MLB 2K13, a game that was panned critically for its stark similarities to its predecessor, MLB 2K12. The confirmation of the series' closure comes after the publisher took steps to remove the brand from its various pages – an indicator that it no longer has the appropriate licensing obligations to fulfill.
As pointed out by Pastapadre, 2K Sports recently took down its Facebook page for the series, videos from its YouTube page and forwarded each landing page for games in the series to its global 2K website. Of the few MLB-branded pages that remain are a few of the game's online manuals, though it's uncertain how long those will be available to view.
Being that 2K Sports was the only company delivering a simulation baseball game for Microsoft's Xbox 360, thanks to an exclusive third-party licensing agreement it signed with the MLB, the Xbox One will be without a Major League Baseball game for the time being. The MLB: The Show series is developed by Sony's San Diego studio, which will launch MLB 14: The Show this spring on PS3, PS4 and Vita.