It's the other way around. There are currently 7000 languages spoken today more than half of which have no written form.
One language is mentioned that has never being spoken. A man named Charles Bliss invented BLISSYMBOLS. It was invented to be used for people to learn so they could communicate with one another through the written word but it never caught on.
Once upon a time there was a language called ESPERANTO. This was supposed to be the language everyone learned so they could SPEAK with one another. Whatever happened to it?
Supposedly over half the languages currently spoken will eventually disappear. Doesn't everything disappear after a long enough "eventually"?