I like this idea but the specific examples you give would almost certainly be a terrible idea. A voice trained on Tolkien or old American legalese like the Magna Carta would train a model with a lot of thee, thus, therefore and though art and undertrain it with modern English. His wife would sound like the second coming of Jesus or Shakespeare and less like a normal human being.
From what I understand, it is not the words themselves (thee etc) but the sounds that make the words - so the "th" and the "ee" are still legit sounds in modern English words. The network would just be synthesising the words you tell it to - it won't be picking the words for you.
