My 2 cents worth:
Firstly, I broadly agree with SBF. The most likely explanation for Watchtower's behavior is that they have significant cash-flow issues.
Secondly, on other threads (which I can't currently locate) darkspilver has given good explanations of why even very cheap labor costs Watchtower a lot of money, and of why donations to Watchtower would be decreasing.
Prior to 1990, Watchtower had huge income from selling its publications door to door; generating great wealth for Russell and Rutherford so that they could live in luxury with their respective mistresses, build and live in Beth Sarim, buy those Cadillacs, go on expensive boat cruises, etc. According to one source, Watchtower was generating around $2 million per week in the mid 1980's from these door to door sales. Now it doesn't have any of that income. It just has donations from an increasingly old and poor (due to a lack of academic qualifications) rank and file.
Darkspilver highlighted costs of feeding, clothing and accommodating 30,000 bethelites. It costs more than a lot of people would think. These people were once essential to the main income earner; the publishing business. Now they are just a drain on the borg. Worse for the Borg, they seem to have a lot of retired senior Bethelites to support. Just for example, see the following discussion on Fishkill:
There are apparently 250 retired bethelites there alone. The annual cost of medical care for this lot, alone, must be in the millions.
Thirdly, Watchtower may well $20 billion in assets (probably more) when you count the value of all the Kingdom Halls. However, as most accountants could tell you, most businesses that go broke, do so because of a lack of liquidity, not a deficiency in assets. Sure, they can sell Kingdom Halls, but they can only sell a few at a time, and only in a way that limits the loss of membership.
Another minor point to add. Printing less literature doesn't actually save much money if you have your own expensive printing presses already. In the early days, when printing involved a lot of manual labor, it made perfect business sense for Rutherford and others to take advantage of the deluded slave labor available. I have no doubt that if Rutherford was running the Borg today, he would throw out all the printing presses and bethelites relating to that, and outsource that part of the operation, or print nothing. I suspect that the operation and maintenance of expensive underutilized printing presses, these days, is just another drain on the Borg.
Overall, I think things will only get more interesting. I suspect they are already burning through the money raised from the Brooklyn sales at a pretty quick rate.