All players in the Internet ecosystem are impacted by the transition to IPv6, including:
Broadband access providers/Internet service providers - ISPs need to update their networks to be capable of supporting both IPv4 and IPv6. This requires running and engineering complex IPv4/IPv6 transition services.
Internet content providers - Content needs to be accessible to newer Internet customers connected via IPv6. This is dependent upon translation solutions provided by ISPs. Content providers need to plan on serving content via IPv6.
Enterprise networks and applications - Need to enable enterprise networks to be capable of IPv6. Mail, web, and applications servers must be reachable by IPv6 in addition to IPv4
Business networks/end users - Routers, gateways, applications, operating systems, etc. may need to be updated. For example, newer operating systems support IPv6 (Windows 7, Windows XP, Mac OSX), but older operating systems (Windows 95, Windows 98) do not.
Equipment vendors - Need to update equipment to meet IPv6 demand. This will be a requirement in future equipment deployed in networks.
Other new opportunities - Sensor networks, smart grid deployment, etc.