Thanks for that informative reply.
No one knows what the model 3 will have for audio support, but the model S can't play audio via USB from your phone, and model 3 probably won't have any features that model S lacks. Once elon musk decides something is "the future" he forces his customers to accept it, whether or not it's actually an improvement. I can easily imagine him thinking wireless is always automatically better than a connected USB cord, even though he's wrong.
I'll look for '14 or '15 gen1's when I'm ready to buy. The gen2's might have improved the controls a bit, but I really think they screwed up the exterior styling on the second generation volt. Looks like an anonymous rental car to me.