Duluth has a huge Twins fan base (including thousands of UMD students from the Twin Cities), and the Huskies (Northwoods League) average around 1,000 fans per game - which is ~150 more than the Snappers. They play in a 100 year old stadium that is up for a renovation that would be guaranteed if they were to be granted a Twins affiliate.
I think a low A team could thrive there. It would expand the Midwest League a bit geographically, but I have been thinking for a while that the Twins should explore it. If an independent league team can survive there, and Duluth has had independent league teams surviving in Wade Stadium for decades, a Twins should do very well. Minor league teams do not necessarily have to be a sunk cost.
A low level affiliate in Duluth would be nice but I don't think the numbers would work. Yes, there is the UMD students to draw from, but classes are usually out during the summer. I have never attended a Huskies game, but I have to question the 1000 fans per game number. With those numbers you would see the nearby parking lots filled more often. During the Dukes most recent tenure here they had attendance problems which led the team to move to Indiana. I remember a playoff game with attendance under 400. While the Huskies have survived here for a few years, these are unpaid college eligible players, not paid players with a payroll needing to be supported by attendance. The 100 year old Wade Stadium is a nice vintage park but is in need of major upgrades to support a MLB affiliate. There has been talk since professional baseball returned in the 1990's to upgrade this park, but the local money is not there to fix it. While the field itself has always been maintained, the seating, concessions and restrooms are not what you would expect to find in a MLB affiliate stadium.
I would love to see a team here. But I just can't see it happening.