It's a nice trend, but I doubt it will have any political impact in the near future. It probably indicates an increase in the number of people willing to admit to non-belief, rather than an actual increase in non-believers. The same people have had the same world-view, whether they were in the closet or out.
Long term, any shift towards the number of people admitting non-belief will be good, because their public presence will encourage others to think differently about their own beliefs, and that will change the actual demographics.
Who am I kidding? I don't understand people anymore. I just don't.