Is it likely to happen? Honestly I have a very hard time imagining the probabilities. Financial collapse versus deliberate destruction versus horrible accident versus actually getting revived? They all seem unlikely, but once your brain is in deep freeze, its fate is one of those.
It's hard to estimate, but nonprofits in the West have OK long-term track records and the cryonics double-organization model has worked well since it was created in the aftermath of Chatsworth (which demonstrated why the commercial side must be separated). Arguably, it only needs to work for another century, and it's not like it's that hard to keep some funds conservatively invested, pay rent regularly, and react once every few decades to a problem.
I'm no neurologist but wouldn't be surprised if there's information in the brain which is encoded in ways other than which neuron is connected to which. Like, firing patterns.