I am afraid I have to disagree a little bit.
The two major ISP-s in the Netherland started deploying IPv6 in their footprints this year so more and more customers will be using IPv6 next to IPv4. One can also check the Google IPv6 statistics to see that IPv6 is on the rise.
The other issue with neglecting IPv6 is that it provides your customers with a false sense of anonymity. Even though IPv4 will be tunnelled using VyprVPN, IPv6 is NOT and this could reveal your identity or activities on the net.
I think Golden Frog really ought to pay more attention to IPv6 because it could be the biggest leak in the VPN tunnel set up.