Obviously as a proxy provider this is something I'm looking into. I've actually been thinking about it a while. I'm not entirely sure how IPv6 maps addresses, but from what I gather this is not going to result in unlimited proxies. While you can get a lot more "individual" IPv6 addresses, it will be just as easy to identify close IP addresses as it is now (as in, ones within the same range).
That said, I really don't know what I'm talking about when it comes to IPv6. I am probably going to be running some tests to see what kind of action I can get with IPv6 proxies. If you're interested in this, PM me.
EDIT: Forgot to mention... this could also be a *bad* thing. With IPv4, there are more connected devices than there are IP addresses. So some (4 billion) devices share IP addresses. Thus, websites are hesitant to ban single IP addresses because they could actually belong to multiple users. But with IPv6, there are so many available addresses that every device can have its own. So you can be much surer that every request from one IP address is coming from the same place.