From a different perspective, I'd be brokenhearted if I could not speak to my son or my wife in something they could recognize as their father or husband's voice. I know modern TTS systems are a fair sight (voice?) better than Microsoft Sam, but it would be emotionally valuable to me to have a self-trained TTS library.
I'm not sure there's a correlation to other senses, I can't see for my future self or move on his behalf. I suppose there are things I would want to taste or smell if I was going to lose those senses, but those are experiences for me, not things I'd use to communicate with loved ones.
After losing my voice in an accident, I'd be willing to spend many, many hours transcribing my own speech in the handful of scratchy family videos, voicemails, and phone logs of ordinary conversations. If I could spend a couple days prior to the event reading some books, a TTS training corpus, or anniversary/birthday/wedding/etc greetings and congratulations into a microphone and have a personal text-to-speech voice I'd be all over that.
It would be a little weird if someone else used it as their narrator, but that's not OP's goal.
Speaking of recording books and training corpuses, my grandparents (who have their voices) got a special kind of joy from reading children's books that they once read to me and that I once heard as a child to their new grandson. OP, if you and your wife have or might have kids (and she can handle it emotionally), it might be nice to record video/audio of reading children's books to future grandchildren. Even if your future grandchild knows that grandma can't read books out loud, I'd bet Grandma would be happy to silently turn the pages for a toddler on her lap until those digital recordings got worn and scratchy like an old VHS.