Have you actually seen, much less tried to ride an Autobike? I've had the experience of working on a couple. YUCK! I think they have fallen out of style because it was basically an overpriced piece of poop.
Actually, my vote for the next major breakthrough in bicycle drive trains is a continuous variable transmission. A year or so ago I read some posts from a fellow (in Germany I think), who was working on one. His idea was to provide a shift lever so that you could control the effort if you wanted to for hill climbing or sprinting. Otherwise, you'd be at a constant cadence all of the time and the bike speed would increase and decrease according to conditions.