So, what's next for Pokemon. R/S remakes? Head straight for 6th Gen?

Crystal was the first try actually.

That would be hard since the events of R/S/E took place 3 years before the events of HG/SS/D/P/P and Black and White takes place sometime after that, adding N to the R/S/E storyline wouldn't be very easy without ruining the past canon and with FR/LG and HG/SS they have done a good job of keeping the past canon intact while adding new things.

But it never mentioned when B/W takes place, as far as I remember.
Just cause B/W comes after Gen 4 doesn't mean it comes after in the time line. See: Gen 2 -> 3

For all we know, B/W takes place before every other game and that could easily set up for an appearance by N.