That area north of the Twin Cities is practically depopulated. People drive distances for shopping if they live anywhere except Duluth-Superior. Rural property taxes are very low, as are values, due to lack of services.
Yes, it is traditional Dem, but so is the Minneapolis-St. Paul area, which holds most of the population. Not sure District 8 plus the western farm areas can overcome the Twin Cities. Lots of fraud in the Cities, too.
Minnesota isn’t really the story here. If Trump can beat Clinton in a heavily Democratic district like MN-8, then he may be attracting enormous numbers of cross-over votes among white Democrats in other battleground states.