IPv6 has been gaining traction both as a necessary service provider technology and as an increasing carrier of Internet traffic. Within Comcast, dual-stack has been an important step to help IPv6 deployment mature and grow. As IPv6 traffic grows and as IPv4 traffic diminishes, we would like to avoid the need to make software changes to enable network features, while also avoiding hardware operational costs that accompany the treatment of IPv4 as native transport in our infrastructure. As such, we are looking at ways for our next generation infrastructure to incrementally evolve towards an IPv6 focused infrastructure. We realize we must continue to support IPv4 for the foreseeable future. Our our thinking is to support IPv4 as a Service (IPv4aaS) — meaning we will carry IPv4 traffic over a “lean” IPv6 focused network infrastructure. In this paper, we detail the insights and learnings Comcast acquired in evaluating technologies that enable or support IPv4aaS over a lean core infrastructure. We also describe how these technologies synergize with current Software Defined Network (SDN) methodologies.