IPv6 will take over - eventually. IPv4 will come to be seen as a legacy thing - but it's far easier accessing IPv4 services from IPv6 devices than it is the other way around (the latter is in practical terms, not possible).
All those workarounds to keep IPv4 "working" have a cost. It's already got to the point where many people (especially in Asia and thereabouts cannot have their own IPv4 address. Many people now sit behind carrier grade NAT (CGN) and that has both complications (a lot of work goes into working around the problems of NAT) and costs (the equipment costs ISPs considerable money to buy and run). The thing is, many people don't have a "working internet" - they have an internet that appears to work after some behind the scenes stuff has gone on to work around the problems.
IPv6 is more widespread than many people realise - it's the default on mobiles for example. Already some sites are IPv6 only.
According to Google's stats, access to their services is now up to almost 29% globally. Look at their per-country stats and the UK is up to 23%, while Germany is up to 43%. AIUI BT, Sky, and Talk Talk all have their users IPv6 enabled by default now - so that's a heck of a lot of users using IPv6 who don't even know it.
The biggest problem is ISPs like Plusnet that appear to be making little (if any) progress in providing IPv6 to their users. Considering that Plusnet is part of BT, it does seem odd that there's such a difference in approach to IPv6.
