The Athletic confirmed (paywall) what a lot of people assumed, the Big Ten looked into possible expansion before forming “The Alliance” with the ACC and PAC-12.
Iowa athletic director Gary Barta:
“We started to talk about, should we ever add any schools to the Big Ten Conference? We currently haven’t said we never will. But in short run, with all things that would have to be included to join the conference, we didn’t identify anybody as a conference that we would immediately go after that would fit.”Iowa AD Gary Barta via The Athletic
Interesting that the Big Ten “didn’t identify” any additional schools. Did Notre Dame not answer their call or did the Big Ten not pick up the phone?