How low would Bitcoin have to fall before it was no longer recoverable?
Price, in my opinion, would not dictate this. It would have to be something that would destroy the foundation and system on which it is built.
what you say?
If bitcoin would go back to $1 that would mean something very, very wrong happened, like a 51% attack or someone getting access to all the wallets and other very unlikely events like those. Going back to $1 also would mean losing 99.99% of the value, at that point everyone would have got rid of their bitcoins and those who didn't probably will stop believing in the project. I don't think something like that could ever happen anyway.