Pascal. whilst looking interesting, might not see the light of day until Q4 2016.
Buy the best card you can afford now. Unless new tech has been given an official release date that's a month or two away I'd not be worrying about it.
The key question, that's been asked already above, is what resolution are you gaming at?
Because if it's 1080p then any money burning a hole in your pocket might be better spent on a new monitor.