First off, they would be in no way obligated to remake the first gen again. That doesn't fit into the pattern they have going as far as remakes are concerned.
First gen
Second gen
Third gen -> Remade first gen
Fourth gen -> Remade second gen
Fifth gen (on the same console as four previous games ) -> Time to remake the third gen
This pattern will likely continue until they hit the point that a remake won't change how the game looks and the amount of content substantially.
I thought this was the pattern...
GB:
Red/Blue
Yellow
Gold/Silver
GBC:
Crystal(current gen revision)
GBA:
Ruby/Sappire
FireRed/LeafGreen(previous gen revision)
Emerald(current gen revision)
DS:
Diamond/Pearl
Platinum(current gen revision)
HeartGold/SoulSilver(previous gen revision)
Black/White
??????
3DS:
??????