As much as I love cars, even if strictly for the mechanical marvel that most take for granted, I'd be all for a return to horseback. They served man loyally for thousands of years, and the lazy idiots couldn't be bothered to saddle one up to go anywhere which alone is worth it to me.
I suppose it helps that I grew up around them, but as it stands now I will enjoy my horribly inefficient and terribly fun to drive automobile. On the off-chance that we return to horseback though, I'll be the guy in the Clint Eastwood 'man with no name' poncho.