Spirit crushing though Eszett's comment may be, I still hold hopes for a G/S/C remake on the DS. I refuse to believe that the only incentive for making FireRed and LeafGreen was Pokemon availability. There was that, true, but there was also the profit that is garunteed to accompany any new set of Pokemon RPGs. Even if it's only a glimmer of hope, I can still forsee remakes in the future due to:
1) Profits. Nintendo showed us last generation that it's not content to just let one set of Pokemon games languish until the next arrives. The Third Generation brought us Ruby, Sapphire, Colosseum, FireRed, LeafGreen, Emerald, and XD. Sure these games served the added purpose of making Pokemon available, and thus added incentive for purchase, but I'm sure Nintendo cashed in big time with these games. We'll see the inevitable companion/upgrade to Diamond and Pearl, but Nintendo will likely want to line its pockets by producing another set of Pokemon RPGs before Generation Five rolls around, and what better way to do that than with Gold and Silver remakes.
2) The references. Yes, they are only references, and yes, there are references to Hoenn and Kanto in Diamond and Pearl as well. However, link is still established with Hoenn and Kanto. Doesn't it seem strange that the most heavily referenced region in the games is one that will be nearly unknown to the young children demographic of the series? Your average elementary school Pokemon player will not remember the days of Gameboy Color, so why would Nintendo throw in allusions that serve only to confuse such a key demographic? Consider the following:
Ruby and Sapphire contained multiple allusions to Johto, among them the fact that the main character had moved from Johto, Johto water samples in the Slateport Oceanic Museum, and others. With the arrival of Emerald, all of the references to Johto were removed, while references to Kanto remained. It was as if Nintendo had decided "Ok, you got your Johto Pokemon back. Now kindly forget that region ever existed." There was a deliberate attempt to remove Johto from the Pokemon continuity. That's fine and dandy, but why pour the Johto allusions back into Diamond and Pearl unless a new plan of action is being considered? I find it hard to believe that there would suddenly be heavy references to a region which the existance of was all but denied in previous games, unless some new plans concerning Johto are being made.
So, the references are indicative of a change in attitude concerning Johto, needlessly confusion for younger players lest they should serve as a prelude to new games, and otherwise unnecessary pandering to long-time fans who would have accepted with Emerald that Johto was no more. Remakes would clarify all of this.