They would panic like crazy, weeping and wailing, throwing dust and ashes upon themselves, ripping their garments, thinking whoever "knew" have all gone to some secret place to hide out until Armgeddon is over.
But I don't see the WT closing its doors (except when the Silentlambs March were lined up front of 25 Columbia Heights... THEN I saw how they CLOSED THEIR DOORS).
Closing their doors, as your subject line says, would be like the WT printing GOD IS DEAD across the front of its mags, and I don't think even the GB is quite ready for that.
They would panic, thinking that the anti-God governmental forces had finally attacked religion, but would immediately flock to their book study groups in private homes, as they have been instructed for so many years.
Oh, wait, they are doing away with book study groups in homes.......
They would panic. They would think it was the end of the werld. They would cry, bemoan, weep, and shit they're pants.
And nothing would happen. For years, nothing would happen. They would go to they're bookstudies, scurrying like rats thinking that satan's gonna kill them like moronic paranoid idiots for many years. After about 20, there would still be some idiots flipping through derelict books that would be dirty, marked-up and smelly.
Pioneers would have to go out and get real jobs, real lives.
Elders would have to find someone else to power-trip on.
The governing body would start a new movement, Jehovahs Witnesses 2 - new and improved.... many would join - most would join Scientology.
The religion is too strong in the minds of it's people for this to happen, so the question is irrelevant in this time frame.
If the washtowel were to go belly up, there would be mixed reactions. Some would commit suicide (those are the ones that already live for the Filthful and Disgraceful Slavebugger, and their lives are already half dead). However, as many would be set free to do whatever they want to enrich their lives and may be prevented from suicide.
Those that are in it to control others would likely form another cult. Chances are, they would try to get as many witlesses as possible in that cult, and they would just carry on as before (as splinter groups). Hopefully, most worldly people would be impervious to the cults' antics after seeing the Washtowel Slaveholdery's.