There is DEFINATELY a problem.
Only about 1% (as an order of magnitude) of the traffic on the Internet is IPV6 - and many (most?) ISP's don't provide IPV6 addresses by default. Even if the ISP does provide an IPV6 address, go down to your local hardware store to see what percentage of gear supports it - you will see that it is comparatively little.
While IPV6 is a cool technology, the net is a LONG way away from being IPV6 capable.
If this is of real interest to you, you should seriously consider multihoming your website so that it can handle both IPV4 and IPV6 traffic (which is practical, and done with DNS). This is the way big providers (like Google) are going. [ To show how backward some places in the world are, here in New Zealand, I CAN'T GET IPV6 on my home connection from my provider - even if I ask - neither can I get it on 1 of my expensive pipes, with the other providers dragging their feet ].