FireRed/LeafGreen's main draw was to collect Pokemon which had not been incarnated into the third generation as of the release of Ruby and Sapphire.I have never been able to understand how for every Johto Pokémon in a new game that is not a Gold/Silver remake, the likelyhood of the aforementioned games seeing the light of the day supposedly drop. If Game Freak wanted to re-visit and expand the world of the first generation in the third generation games, did it mean that the Pokémon introduced in the second generation had to be wiped off the face of the earth until those three years had passed again?
Considering all old Pokemon are available in Diamond and Pearl, I can't see the appeal of making a GSC remake at this point - Lugia and Ho-oh more readily available? Not to mention the other flaw with such remakes. After recently visiting Kanto, do we really wish to revisit the land again so soon? They'd either have to wait for a while or scrap the Kanto region entirely and construct a new Sevii Island-esque island chain to explore.
Better to save it for next generation, methinks. In Generation III, GF constructed an artificial need for Gen I remakes. There's no need for them this generation.