You have the technical answer, but I think the more useful answer is human based. Content providers will stay dual stack basically indefinitely - abslutely no

You have the technical answer, but I think the more useful answer is human based. Content providers will stay dual stack basically indefinitely - abslutely no website operator wants to lose even 1% of their traffic due to a technical limitation, so I do not expect demand for v4-enabled websites to die off any time soon. I would expect 95%+ v6 usage before you even see this being a thing commercially, and even at those numbers only very small marginal operations will go v6 only. The consumers and consumer ISPs have both a better technical solution, as well as no consumer ISP gives a shit if their customers can't access 2% of the internet. Therefore the change due to both technical reasons and simple game theory must come from the "eyeballs" side of the equation.