To some degree, progressivism has exhausted itself in Minnesota. The state has top-notch education and healthcare systems, its civic life is vibrant, and overall governance is active and efficient. People (especially the suburban middle class) tend to take these things for granted, however, and after the economic troubles pass you could see a swing to the right. If, furthermore, rural areas were to experience some upsurge of social conservatism then the state as a whole could be favorable to the GOP in the future.
Good point.
Someone (Hubert Humphrey I think? Sleep deprivation....) once said something along the lines of that Democrats are a victim of their own success; Democratic policies improve the economy and reduce income equality and the resulting increase in average income causes people to vote more Republican.
The 2000 Presidential election would be another example of this. The economy was so good after 8 years of Clinton that it was a non-issue, allowing the focus to shift to social issues which favored Bush.