TradMan80, you say they will get most of them. Maybe from the indult but not from the resistance, Pius V, SSPX, home aloners, or any sedes. (which are all growing)
There aren't a lot of young people in the NO, at least where I live, and I don't think the indult crowd is strong enough to have their children keep them in business when they're gone.
Even their seminaries are near empty.
So just how long can they continue operating? 10 years?
I don't know what it's like in other places, but here, devout NO who've been away from Mass for the last 18 months are now quite comfortable staying home and a few I've spoken with will not be returning prior to their funeral. I think they forgot about them in their plans for financial support.