I think Iowa's ceiling is about the same as Wisconsin's. And Wisconsin is about at that ceiling, right now. Maybe they can sneak in, someday, when OSU (and PSU, but mostly OSU) are down. MSU seems to be in a state of flux right now.
Michigan is no longer a threat. Wisconsin is the better program right now, and has been for some time.
Can Michigan beat Wisconsin? Of course, but not in Madison. OSU and PSU can, and have. In the 9 games since UM last won a conference title, they are 4-5 against UW - 4-1 in Ann Arbor (mostly close games) and 0-4 in Madison (mostly blowouts).
Wisconsin has won 3 conference titles since Michigan last has, and has played for 4 more in Indy. Michigan has never been to Indy - even when they were in an opposite division from OSU.
Iowa could replace Wisconsin as the team to beat in the West, for sure. The jury is out on the rest of the division doing that.