This is so not new... RFC1335, May 1992 A Two-Tier Address Structure for the Internet: A Solution to the Problem of Address Space Exhaustion http://www.faqs.org/rfcs/rfc1335.html Many others have followed since to stave off disaster and another one will, probably already has, been proposed.
All commercially available operating systems have had dual IP stacks for quite some time now. For those that don't there's a fist full of IPv6/IPv4 translation layers that your packets have already been hopping through for a couple of years now. When the time finally comes to switch IPv4 off for good it will be as uneventful as Y2K and the switchover to digital cable were.