Chip:
Milwaukee CC is a very low-key course; it surprised several in Wisconsin when it came out of hiding (sort of) and agreed to host (along with neighboring Brown Deer, the muni that hosts the PGA stop in Milwaukee) this year's Mid-Am tournament. I be surprised if the membership there would be interested in the headaches involved in hosting the US Open -- maybe the US Amateur, and it'd be a neat, Golden-Age course ala Interlachen to host the Women's Open. But I'm not sure it can be lengthened to today's USGA standards for the men's Open. (I don't specifically know what kind of lengthening options it has, but it's on a pretty tight site.)
I believe MCC is Alison only, not jointly w/ Colt, although it's often attributed that way.
(I'd say the same thing about Canterbury -- very good course, good pedigree, a Herbert Strong layout, but short by today's standards. A good US Am/women's Open choice, but probably not the men's Open.)
I'm certain Erin Hills will be the site of a US Open in Wisconsin, if the USGA awards one to the state. Herb Kohler cast his lot with the PGA by garnering two PGAs and the Ryder Cup at Whistling Straits, all in the next dozen years or so. And Erin Hills isn't all that far from Milwaukee -- it's sort of on the very outskirts of the greater Milwaukee suburban area.