Well, first you need to change Nintendo to Game Freak, and besides Game Freak doesn't make many World Wide games, (I believe Pok�mon is the only =\) but anyways I think Game Freak has a plan to remake Gold and Silver (not Crystal because it was a special edition as was Yellow), but anyways as Master Volthawk posted above, Game Freak has entitled the new games Ruby, Sapphire, Emerald to actually carry many of the Jhoto pok�mon, but I think maybe since Jhoto was a more popular Game Boy Color title, and had so many other advanced features, they decided to not remake the games until a 10 year mark, just like Red and Blue was done, but Blue was changed to Green instead (have really no clue why though).
But if they made a Blue version complete remake, it would have probably consisted the name Pok�mon Ice Blue, which really wasn't appealing to the viewers, so they picked Green, standing for Pok�mon Leaf Green.
Anyways, Jhoto was a bigger region than Kanto and Hoenn, and as Game Freaj remade the old titles Red and Blue into Fire Red and Leaf Green, they had other titles such as the future DS games, Pok�mon Diamond and Pearl, so I really believe there might be a Pok�mon Cold Silver and Pok�mon Heat Gold for the DS, instead of on the GBA, but this is only my theory of the Pok�mon cycle.