The Internet of Things (IoT) is an ongoing next technological revolution impacting all application domains. It is expected to be massive and pervasive, with over 50 Billion smart things and objects connected by 2020 [1],- and more to come. It will impact many application domains, from agriculture, to smart cites, industry, energy and transportation. The precise number of IoT motes on a longer term is not realistically predictable. However, we can ascertain that it will be massive and growing. Interoperability has been identified by the International Telecommunication Union (ITU) as a prime requirement for the IoT. The adoption and growth of IoT technology will be directly related to its capacity to overcome its current fragmentation with addressing solutions able to handle very large scale deployments. In this context, the Internet Protocol version 6 (IPv6) is emerging as the most credible candidate in terms of network protocol. Beyond its global adoption and availability through the Internet, it is characterized by several qualities that constitute a good match to address some of the main Internet of Things requirements: • Scalability, with 2^128 IP addresses; • Self-configuration, with its Stateless Address AutoConfiguration Mechanism (SLAAC) [2]; • Mobility; • Security enablers, such as IPSec; • Lightweight adaptations IPv6 stack for constraint IoT motes with 6LoWPAN [3], CoAP [4], 6TiSCH [5], etc.; • Global availability and interconnectivity thanks to the Internet infrastructure; Over the last decade, the author initiated and was associated to several research projects addressing the convergence between IPv6 and the IoT, including inter alia: • Universal Device Gateway, a Swiss research project researching the potential of IPv6 to support multiprotocol interoperability for the IoT; • IoT6, a European research project exploring the potential of IPv6 for the IoT and for cross domain integration; • Hobnet, a European research project exploring the potential of IPv6, 6LoWPAN and CoAP to support smart buildings; • IoT Lab, a European research project exploring the potential of Crowdsourcing and IoT for research, as well as the potential of IPv6 to federate heterogeneous IoT testbeds; While the IoT industry seems to converge towards IPv6, there are still questions related to the effective capacity of IPv6 to address an exploding demand of a massively growing number of communicating devices. The present article intends to provide some clarifications on this matter.