Years ago, a friend of mine's mother-in-law lost her voice due to cancer. As an engineer, he built her a tool from a toy Casio keyboard and some samples, allowing her to talk using this portable toy.
After that experience, he talked about wanting to create a service by with which people could archive their voices, so that in case of future need they could be loaded as samples for such a device. He'd give them scripts to read and record, from which he'd parse the phoneme samples, and then storing them in a repository that they could later retrieve if necessary.
Today there's probably a need for a lot more security than he'd talked about at the time, but it seems like something that's eminently do-able today. It could be a very cheap and low-cost endeavor, but useful as a sort of insurance because it carries a really high value in the unusual cases where it's needed.