Hmmm... let me think this one through. Imagine a scenario where the WTS continues to emphasize donations directly to the worldwide work as opposed to supporting local Kingdom Halls. There's a real problem with going down that road - they need to strike a precarious balance. They need the local KHs to operate in order to have regular "sales meetings" to keep people active and in fear. If the congregations started to dry up, they would feel the pinch. I think in the long run if they could avoid having local KHs which are a drain of publishers money, they would give them up as long as it didn't affect the bottom line.
But they know they can't. You need to keep a sales force active out in the field. Tough balancing act they are trying to pull off.