IPv6 has already gained critical mass. The CDNs are all turning on IPv6. The wireless ISPs are delivering the Internet over IPv6 today translating connections to IPv4 to talk to legacy servers. Sensible fixed line ISPs are delivering IPv6 today as it cuts down the CGN costs. The biggest players on the Internet are using IPv6 only internally translating connections to IPv4 to talk to legacy servers. IPv6 is not going away. It will just grow and grow.
When a home becomes IPv6 enabled (basically replace the CPE with one that supports both IPv4 and IPv6) most of the traffic switches to IPv6.