Although 2K Games has the exclusive MLB rights to publish 3rd party baseball games (I hate them), there will be another baseball game coming out.
989 Sports is able to come out with a version of an MLB game because it is owned by Sony and is considered a first party publisher.
I for one will pick this up. I picked up last years 989 game and although it wasnt graphically up to snuff with MVP, it was a fun game to play, and in a lot of ways, more realistic as it didnt really have the arcade feel that MVP has to it (the catcher also throws the ball back to the pitcher in this game after the ball is pitched unlike MVP, a minor thing I know, but it still bugs me). I'll probably pick up MVP '06 as well because I'm a baseball video game nut.
MLB '06: The Show Official Site