"won't be long before websites *demand* that you access them over IPv6"
Huh? Given that countless thousands of websites can be hosted from a single IP address, I don't see any pressing need for websites to try to push people towards IPv6 access, even in countries that are by necessity adopting IPv6 well ahead of us laggards in the US and UK.
Why would websites demand IPv6 access? What's in it for them? How does reducing their potential audience benefit them in any way? How much more could their hosting provider really charge them for the use of a tiny fraction of one IPv4 address?
I wouldn't be shocked if I could carry on ignoring IPv6 and using IPv4 alone for the next twenty years. Maybe it'll stop working then, because of unfixed Y2038 problems that were ignored because "no one will still be using IPv4 by then".