Potato blight does not usually survive cold weather, and the Irish blight is usually attributed to the fact that the Irish grew a very restricted number of potato varieties.

It's not a disease that I'd expect to continue unstoppably forever: a cold winter, burn the infected foliage, perhaps fresh seed potatoes (maybe more blight-resistant ones) and away you go... Most potato growers get a bit of blight from time to time, it's always floating about.