I'm surprised it's lasted as long as it has. All the doctrinal flailing has rapidly increased and the retention rate among the young is abysmal, they're losing about half. Also, moving operations to more remote areas is often a sign of a cult in leadership crisis.
They're trying to soften some aspects like blood and meeting, preaching requirements, but at the same time tightening their grasp on claims of being the only channel of salvation.
There's even indications that there's dissention of thought among the GB...I've been getting "acts of desperation" vibes from the WTS for the last 5 years...maybe even longer.
I think it'd be premature to set a date, because unlike them, I don't claim to be a prophet. But, they're in trouble financially and of course, authoritatively and spiritually, I have no doubt of it.