Won't happen, there will always be a band of "faithful" JWs. The Catholic Church has been sued to the kazoo lately, and in spite of the word "bankruptcy" being thrown around, it is still a powerful and viable organization. The WTS may get smaller, but it won't disappear. That's what happened to the Worldwide Church of God (WWCOG)(Herbert Armstrong).
BTW the KHs are not owned by the local congregation in the same way I own my house. They are a non-profit organization. When the congregation dissolves or is dissolved by the parent non-profit corporation, the property reverts to the control of the parent non-profit organization, the WTS. The government wants this to stay non-profit and property/cash not revert into an individual(s) pocket.