Apognophos - "They would give it up only if they lost their special status. Say, if a combination of the removal of tax-exemption from the Society and other factors caused a financial dissolution, and/or they lost most of their followers due to doctrinal upheaval."
It's been pretty heavily documented that doctrine is rarely a significant factor in an ex-fundy's decision to leave. Financial dissolusion, though? Maybe; it's happened to Wall Street traders who lost everything in a stock crash.
Apognophos - "Alternately, a persecution situation (even if not part of a broad UN move against religion, but targeting only them, and even if they brought it upon themselves through Rutherfordian rabble-rousing) that leads to a literal Hitler-in-the-bunker situation could mayyyybe prompt them to shuffle off their mortal coil a little sooner to join the bride in heaven."
Again, (like you said) maybe.
According to Fred Franz' eschatology, the "Wild Beast" is supposed to attack the WTS after it destroys "Babylon the Great" (not before), but that could arguably be retconned as "New Light" (although it might give pause amongst some of the more prophecy-inclined rank-and-filers).
And at this point, they don't really need to engage in Rutherfordian rabble-rousing (I love that; say it real fast five times) to provoke the larger world around them; the rising tide of pedo lawsuits might just be enough to make that happen regardless. The justice system has been known to make an object lesson from time to time, and the WTS is a very convenient candidate, since they have no influential friends in high places (in the real world, anyway), they're relatively small and a legal spanking wouldn't negatively impact the larger socio-political environment around them, and they're kind of unpopular already anyway, so no one would really feel much sympathy for them.
Assuming something like that actually happens and things really do go south, and they do decide to bunker down in the new Warwick HQ with a dutiful staff of 1000-odd loyalists (IMO, the mentality is already present), I can see some of the less rational ones advocating some kind of "liquidate-all-the-property-cut-the-congos-loose-bolt-the-doors-and-bunker-down" course of action; maybe even literally (instructions, I might add, that would definately seem "impractical from a human standpoint"); perhaps even to the degree of convincing themselves that the Great Tribulation has actually arrived.
After all, virtually every scrap of insider info we have indicates that they're full-on True Believers, and a strong argument could be made that the internal structure of the GB has already reached the point where no one on it can really challenge WT policy anymore, anyway; by now, they're already fully committed, and the rudder's way too rusted up to make tight turns.
Of course, when the days turn to weeks, and the weeks turn to months, and the World still stubbornly refuses to End, and they start feeling more and more marginilized, and dissent begins to manifest itself even amongst the loyalists, and quiet desperation begins to set in, the Kool-Aid option would definately start to look more and more appealling.
I could be wrong.