I think there are too many variables to be able to guess much of anything. First of all, you may well have already carved out a niche market for yourself. You are an independent NP, not part of Medicare, very possibly not deep in the pockets of managed care. If you are making it under those circumstances, then I think very possibly little will change in the short to medium haul. I think it also greatly depends on the kind of area in which you practice. Articles such as the one John describes are very applicable to an urban setting, but much less so in a rural area. Marysville may be far enough away from Seattle to insulate you, although the big clinics are very hungry, and happy to set up satellites.
Add to that the uncertainties of the eventual fate of he Affordable Health Care act, and there is still just a huge question mark. But, there is certainly cause for concern if you are within striking range of the big Seattle clinics.