And who says it can't understand the material? There have been recurrent networks trained that can translate between languages, or predict the next word in a sentence, at remarkable accuracy. Combined with wavenet this could be quite effective.
There could be cases where the intonation is dependent on things entirely outside of the book. If say a politician does something in the writing that is far from what we would expect them to do in today's world.
Like traditional audio books can capture perfectly what you're referring to...
They can, though?
How about we allow annotation of text with prosody cues? Mark the words you want stressed. We already use question and exclamation marks.