The WTS can go on for years simply on the fact that the majority of the the members are held mentally captive and will ignore the glaringly obvious time after time after time. I think this will be the case even with stagnation or even growing losses.
Having said that, the youth in the organisation, whilst following patterns set by previous generations, do not have the investment in the organisation that their parents have and are far more likely to be more apathetic and liable to investigate the religion on the internet. I can see from what is happening with young people I see all the time that the desire to focus on a life in WTS centric activities is low. When I was a teenager, it was more common for young men to be "reaching out", now I think the balance is the other way - few young men are that interested in pushing to servants and elders.
I am certain that the GB can see the writing on the wall and are trying their best to stem the flow with increasingly desperate measures like banging on about loyalty, keeping the pressure up on shunning, shameless emotional blackmail through saccharine paradise videos, spreading FOG through things like the bunker videos, eking out time through change and distraction, demonising those who question and so on.
It's true they have always done much of this however the recent changes to the WTS have seen them move to highly emotional messages using video. This is way different to the past. The problem for them is that this is low hanging fruit. It's captures the attention and the minds of some but only for a short time before reality kicks in again. Not only that but for any who don't buy straight into it, it simply breeds cynicism and opens the door for critical thinking. It's a short term strategy and i wonder how long it can really last as people get increasingly frustrated with the lack of real depth to anything.