While I hope that they collapse soon, I am doubtful that it will happen so quickly. They are still flush with money and have a loyal base that should keep the numbers steady for a few years at least. I think it's more likely to be a slow process. But that also depends on how well they adapt to a changing world.
It's much easier now for people to learn about the WTS, including any doctrinal issues and the parts of the past that they seek to hide or ignore. I think that's one reason why so many young people --especially those born in-- leave the organization each year. The problems are out there to see, and the warnings sometimes make it seem as if they have something to hide (and a bit of searching shows that they do!).
They need to be able to manage the fact that people can now learn all about the organization's history before deciding to make a commitment. Can they do that? I'm not sure about the current GB. A new and younger GB, which is perhaps more tech-savvy, might come up with something that works. Or they could accelerate the decline. We'll see.