Copying existing voices is the silliest use of this technology. Why do I want another fictional character to sound like Nolan North?

Hire Nolan North anyway, but make him sound like whatever the hell you want. Let artists create the voice they hear in their head for this character they've invented. Use a real actor to get the performance, not the raw recording. Then if you need some throwaway lines added later, you don't need to call the big-name actor back in, you can have anyone do the character.

This is turning the human voice into an instrument that anyone can play. No kidding it's so-so if you just text-to-speech some generic dialog, or put sheet music into a MIDI. Talent matters. But now it can matter the way guitarists matter, rather than the way singers matter. Alex Lifeson could join Cannibal Corpse. Geddy Lee cannot.