They will probably make a few more Spin Offs like Mystery Dungeon - Magnagate & the Infinity Labyrinth before they go to 6th Gen. Some times we can tell the way the games go by where they are in the Anime and apparently the League is coming soon so they will probably rap up 5th gen at least by I think the beginning of 2014 since BW came out 2010 and it is usually a 4 year gap between gens, although there will have to be a hefty filler saga for the anime since it is about over.
I figure we will start RSE remake coverage around the beginning or middle of next year and they release it in the Fall.
I adamantly believe we will see a sixth gen, because for me dying by 2015 seems quite absurd considering how well the sells of the games still are and have fast BW sold. I don't feel like we need a MMO, a game with all the regions, or anything so far out. We just need innovations that we have got through out the generation. They kept the same basic formula throughout all these years. They already shown they could be innovated with two 3rd games that are a sequel to the first games which has yet to be done.