ISP's can already do that... by repackaging IPv4 traffic into IPv6 (when I worked at an ISP this was an experiment that was being done to test the viability to

ISP's can already do that... by repackaging IPv4 traffic into IPv6 (when I worked at an ISP this was an experiment that was being done to test the viability to reduce IPv4 address requirements across the backbone, but you could also tunnel it over IPv4 I guess) so that the traffic traverses their entire network inside an IPv6 tunnel, and would get translated back to IPv4 on the edge. As a user you lose some visibility in terms of what routers your packet traverses, but the same can be said about MPLS tunnels/IPSec tunnels where your packet magically seems to have gone just 1 hop instead of the 10 it actually took.