Thing is, there has never been a Pokémon generation split between two consoles (and before anyone brings it up again - although Gold and Silver worked on a Gameboy, they were marketed as Gameboy Colour games). The main thing is though, GameFreak don't have to release a Ruby/Sapphire remake only "before the third version" or "directly after the third version". In my opinion, the timeline will go something like this (Japanese release dates):But...R/S remakes wouldn't have new Pokemon, so what would make it not just Generation V if the console has no effect on it?
2012: Unova 3rd Version (DS)
2013: Generation VI Primary Pair (3DS)
2015: Ruby/Sapphire Remakes or Gen VI Third Version (3DS)
2016: Ruby/Sapphire Remakes or Gen VI Third Version (3DS; Whichever wasn't in 2015).