Many customers/companies depend on their ISP for Internet connectivity. This is a serious argument. Of course one option may be to switch to another ISP, but that is not always favoured, e.g. when the contract limits the possibilities, or switching to another ISP requires renumbering of the network. It would be good if ISPs would publish their IPv6 roadmaps. Companies would then be able to line up their IPv6 migration plans against that roadmap.