The IAB has published RFC 8170: Planning for Protocol Adoption and Subsequent Transitions.

Abstract: Over the many years since the introduction of the Internet Protocol, we have seen a number of transitions throughout the protocol stack, such as deploying a new protocol, or updating or replacing an existing protocol.  Many protocols and technologies were not designed to enable smooth transition to alternatives or to easily deploy extensions; thus, some transitions, such as the introduction of IPv6, have been difficult.  This document attempts to summarize some basic principles to enable future transitions, and it also summarizes what makes for a good transition plan.