I think WT needs to clarify what its goals are.
If the goal is to maintain a high control religion/cult then they'd better figure out a replacement for door to door work.
It keeps people too busy to think logically about the whole thing and keeps them in the organization. It's a great coercion tactic.
But, what if the goal is to simply keep the money rolling in?
That can be done successfully without needing high control or coercion. Plenty of religions stay in business with parishioners voluntarily donating money.
People need to feel like they are getting something, though. A feeling of community is something many people seek from religion. It seems to be the reason lots of JWs are stuck in.
It seems WT needs to fine tune the way to keep people in voluntarily and donating by giving them something of value. People want community. Find ways to provide that feeling, drop the religious coercion, and, bingo, the money will still roll in.
Most people are no longer interested in convoluted religious ideas and are still in because they are held hostage. That is WTs problem. That is the cause of their falling numbers and bad PR.
It's basic marketing. You have to create something people want before they'll buy it voluntarily.