Well, if Gamefreak releases more Pokemon games, they're probably going to be on Nintendo systems since Pokemon is copyrighted to Nintendo. That's the same reason why there aren't Mario or Zelda games for Playstation. Those games were made by the Nintendo company, and they'll make more money if you have to buy a system made by them to play a game made by them. There have and may be more Pokemon games for the PC, but I doubt they will be "color version" games like R/B/Y/G/S/C/Ru/Sa/Fr/Lg/D/P.