I think it's eminently realistic to do a HSR line from Chicago to Minneapolis for slightly sub-three-hour service. You build it on quite a direct route, with grade separated interchanges with the existing network at strategic points -- maybe Watertown, Portage, Tomah and La Crosse. You also serve Rochester to add an important intermediate destination rather than Red Wing and Winona which are much smaller towns that in any case are already connected to the Twin Cities by passenger rail. From Watertown to Chicago O'Hare or so, a direct diagonal. From Watertown north, basically the CP route except for the Rochester deviation. In the Milwaukee area, simply quad-track and boost the existing routes to 125mph.
The key is that the HSR line would be able to support multiple service patterns if existing lines are developed and electrified. You might see a Chicago to Madison service using the HSR as far as the Watertown exit, or a Milwaukee-Minneapolis service using the HSR line from the Watertown exit to the St. Paul terminal, or a Winona/Red Wing local picking up the HSR at La Crosse and then running express to Madison and points beyond. This is how you economically maximize the utilization of the asset. Any one of these city pairs might only support hourly service or worse, but combine them all and you see that at least on the central section of the line from about Portage to LaCrosse, it would be very busy.
You don't necessarily have to make the HSR line cross the edge of every minor metro area. The Rochester, MN primary census area only has a population of about 181,000. Maybe it would work just as well to build the HSR line as a straight shot from Madison to MSP, and upgrade the 20-25 miles of track from downtown Rochester to the HSR line to ``110 MPH''. Those 181,000 people might experience an extra 15 minutes of travel time, but the millions of people in MSP going to see the millions in Chicago might appreciate saving a few minutes not having to go so close to Rochester.
An added benefit of making the tracks from the edge of Madison to the edge of MSP as straight as possible is that if those tracks can be built entirely without curves, and not too close together, upgrading the tracks for faster speeds as they become available will be straightforward. Someday we might have 550 MPH trains running on the long straight segments; if the have to slow down for 220 MPH curves every 50 miles, those 550 MPH trainsets may not be able to make very many miles at 550 MPH.
I'm also not sure why the Madison local tracks to HSR connections should be so far out of Madison as Watertown and Portage. I'd think you could get the HSR line somewhat closer to Madison without significant interference with thickly settled areas.