I've attended Canes games hosting Notre Dame since the late '60s as a kid. The crowd has never been 50/50. Even when they had Parseghian and we owned a typical crowd of 20,000 and no chance to win it wasn't 50/50.
Maybe 10-15% this time, with preference to the low end.
They will be scattered and not all in one spot. Kind of like the Nebraska game from 2015. When things go well for Notre Dame the fans will be loud enough and spread out enough to make it sound like above 10-15%. That's the fooler, and it will likely fool television viewers and biased commentators sitting in a faraway studio somewhere.
The subway alumni are a more obnoxious fan than the South Bend variety. That is particularly true in the USC/Notre Dame rivalry, which alternates home and home. USC fans are often stunned when they make the trip to South Bend for the first time, because the Irish fans are actually civil and classy. There was the standard related thread on USC forums after that game a few weeks ago. Nothing but praise for Irish fans. Of course, they won huge so not much to complain about. But when USC hosts Notre Dame then it's morons galore supporting the Irish. I was shocked the first time I experienced it as a USC student. Those subway alumni swarmed our campus on Friday and wouldn't shut up until we finished kicking their *** a day later. They loudly disturbed our pep rally and everything else. I wouldn't be surprised if similar is attempted on campus with the Canes, although I have never been a Miami student and seen how it plays out when Notre Dame visits.
From my one trip to South Bend when the Canes visited, there is more animosity in this series than USC/Notre Dame. Fans who would have looked away or even smiled if I had been in USC garb felt compelled to attempt a wisecrack since I was in green and orange.
The key word is attempt. I tend to fare quite well in those brief verbal jousts. They were pathetically unaware.