You have no idea how much of a "way of life" pearlshipping can be. I remember that back in 2009 I was fully absorbed in supporting the pairing. In the period from mid-2009 to early 2010 pearlshipping truly was in its prime. SatoHika moments were present in nearly every episode. And most of the time, those were brilliant moments.
The future seemed so bright back then...
I'll tell you what. it's unlikely that generation 6 will last only three years. If XY is as fast paced as BW was, Ash might have been done with the league after, say, 2 years from now, with some sort of a filler saga following where it could be possible for older characters to show up. And I don't need to explain that Dawn should be the top candidate to reappear if an opportunity arises. Wishful thinking? Perhaps, but speculating and reaching is all what's left.
If pearlshipping can't happen, I hope that the writers at least won't have Ash end up with any other girl, so that SatoHika can go down in history as undeniably the strongest Ash-involving pairing. This, obviously, would be by no means a satisfying outcome but what are we supposed to do? Beggars can't be choosers.