Hard disagree. Phones and computers do text/images/video. Voice input and audio output is a poor substitute for text and not at all a replacement for images/video.
Today's smartphones have to evolve this way, imo. I don't know what the most efficient hardware realization would look like but I imagine it's something that isn't in your pocket most of the time, more of a sleek wearable. It will need to be able to hear and see what you do.
Not that I'd be advocating this for library study halls!