For the rest we provide a static IP address, so we'll allocate a /30 (block of 4), and they get a single usable address which they will assign to their own manged router/firewall.
For the majority of our customers "networking" is either handled as overflow for their in/out IT resource or often by someone remotely savvy with tech.
For most of these people networking ranges from an infrequent concern to a vague mystery that can be sorted with a bit of googling.
For most, deploying and testing IPv6 has absolutely no upside and quite a bit of potential downside, that's because "everything works" on IPv4 and configuring IPv6 is just another potential source of error.
In addition, most people who opt for this setup do so in order to expose some internal service to the internet (port forward), again there is usually zero incentive to also deploy IPv6 as they can't be sure their client device will be using v6 when they come to connect, but they know it will support v4, everything does.
And so herin lies the issue, it's chicken and egg, they know they need v4, not every server they access or client who accesses their forwards supports v6, so they _have_ to implement v4. As such they see no reason to "faff" about with IPv6, and I don't really blame them.
We're considering charging more for dedicated v4 and possibly offering a free translation service (another point of failure :() but honestly, most would just pay the extra and then just resent us a little more. Our competitors continue to acquire v4 space as we do, this is what our customers want.
Until there is v6 only content (but who is incentivised to do this?) then I can't see any incentive for these users.