Interesting that this has nothing to do with ride sharing (or at least the article doesn't cite that as a reason). I think autonomy and ride sharing will drive used cars nearer to the value of scrap metal within the next 5 years.
I expect full autonomous driving to be much further out. Where it could have an effect though is this. To the degree that new vehicles become much more attractive because of new sensor and software features, that would likely drive used car prices down. These could certainly increase the perceived value of a current model year car vs. one from five years ago.