My ISP (Verizon FiOS in NYC) does not offer IPv6 support at all. Users have asked for years. They've promised it for years. It's still not there. So it's not a matter of users asking. Re switching, I think I have one or maybe two alternatives; I'm not sure if they support IPv6 either, and they have their downsides too.

Any potential killer app is going to have to decide whether they want to lose such users, because I cannot imagine an app that is so compelling that I'd switch ISPs for it. And I'm a person who actually wants IPv6 for its own sake. I certainly cannot imagine, say, my parents switching ISPs over an app (and I'm not sure how much choice they have either).

And if such an app arises, it's going to be easy enough for users to use VPNs - it's already common for people to use VPNs to get to region-locked content or (at least as of a few years ago) play LAN videogames over the internet.