Bottom line: the number of people willing to fund the organization, for the long term, is most likely a small, aging percentage of the declared WT number of JWs. And it's a worldwide figure, with some countries able to produce more funds than others.
So what's that percentage? Very hard to tell. We hold our finger to the wind as exJWs. We see people come and go. know that every single young person, save one, that I grew up with has left. I've seen elders just give up and leave - which was probably a brewing PIMO situation for a while.
So what's that number? If it's 20%, then the organization will collapse to 20% of its size. Doesn't matter what they do with the doctrine.
I have a feeling the actual number of true, long term funders and believers is a lot lower.
This is why they feared the internet so much. Too late. It's going to shrink, far. It's just a matter of time. And as time lurches forward, and this "old system" sticks around longer, the percentage willing to fund the org will decrease. The old guard will die, replaced with ever dissolutioned younger folk itching to get out in the real world.
Time and pressure... time and pressure.