The biggest problem IMO the collapse of non orthodox Judaism. The reality for many people Orthodox judaism isnt going to work (If it were people would be flocking to shuls, keeping Kosher, Shabbat, but they arent)
Charedism just isnt right for everyone, otherwise there wouldnt be OTDers. People dont leave if they are happy.
While there might be 1-4% of BT’s there are probably a similar number of OTDers so that probably cancels each other out.
A way must be figured out how to keep people who do not want to live the Charedi lifestyle in the fold