I actually think the BBs can drop out of that status, it may take longer now than before. Imagine a BB Team averages 7 wins a year for 20 years, while say Clemson averages 11 wins a year over that period. And the 7 wins includes no seasons with more than 10 wins, no major bowl wins, not really much of anything. And of course high level recruits start dropping them from preliminary consideration. That is the spiral drain right there, coupled with not having found a coach they keep for more than five years.
Maybe it takes 30 years, dunno.
I bet 5 star guys already have Clemson on their short list, and not Michigan.