Audio has been around since, I suppose, the spoken language. The difference now is distribution and availability. Audiobooks, podcasts, smart phones, voice controlled home speaker systems, connected cars, and who knows what will come next.
My only concern with using dictation is how my mind, and how my imagination, will adjust to it.
This is where things can get exciting with your book as a podcast as opposed to (or in addition to) an audiobook.
When I first opened the Audacity program I have to admit I was intimidated.