My interest was piqued 20 years ago, then there was talk about Internet2 with all these amazing optimisations.
Things have developed so much, a Internet2 is still going on I take it, however is more focussed on university research.
As ever a killer strength is something that draws people to a new technology, I imagine there's various demographics that benefit from use of ipv6.
Further I imagine that there are some levels of criticality which when reached are more self sustaining (dare I say it the network effect?).
I've been posting this graph over the years, and it really has slowed down hugely close to this 50%. This is a global ipv6 support, so some countries are racing ahead, others weirdly like Denmark have a stash of ipv4 addresses and seems content.
France and Germany are at about 80%, but there's the rest of the world of course.