What if they surprised us and not make a 3rd version and skipped to a remake or something... Like if we had R/S (no Emerald) then FR/LG that way it's the same gen, has small new features, two games (ala B2/W2) while being a new journey. But the chances of this are probably small.
The 3rd rarely follows Red + Green => Blue? Red + Blue => Yellow at least makes some sense Silver + Gold => Crystal? (shouldn't it be Platinum) Ruby + Sapphire => Emerald makes some sense Diamond + Pearl => Platinum? (shouldn't it have been Opal, another gemstone, with girasol as a type of opal?)
Red, Green, and Blue makes perfect sense
For those of you starting topics about the PS4, there's a PS4 board: http://www.gamefaqs.com/boards/691087-playstation-4