Why IPv6 has not been deployed on a large scale is discussed by Geoff
Huston in this article for the Cisco Internet Protocol Journal. Huston
examines the timing of the IPv4 address exhaustion and the nature of
the intended transition to IPv6 as well as considering the shortfalls
in the implementation of this transition, and identifying their
underlying causes. Finally he considers the options available at this
stage and identify some likely consequences of such options.