So, this is mostly true. There is plenty of free IPv4 space, it's poorly managed and a lot of it is actually dark. I've done some research in the past few years and you'd be disgusted by the number of dark-for-over-a-decade /16 blocks are out there. While this is true, it is pretty much irrelevant. While we (North America primarily) are holding on to our IPv4, the rest of the world is in the middle of the move to IPv6. The content is there. I have graphs to prove it. My guess is that if you ask AT&T, they'll hand you a v6 peering. Often they don't volunteer it, but even cogent will do it.....if you ask.
Even on my entry grade comcast cable modem connection in the middle of nowhere I get a native IPv6 delegation.
I completely disagree with the statement that IPv6 is a quagmire. It's just another protocol. It's no more complicated than IPX, in fact, I'd say that it is actually easier to manage than IPv4. It's smarter, it is built to be hierarchical, it handles all of the messy add-on stuff from IPv4 natively [with the exception of DNS server handoff....still a small work in progress] but with DHCPv6, which you're going to want to do anyway for accountability, that's a non-issue. I've renumbered backbone links with zero impact in the middle of the day because IPv6 is smart. It uses link local to communicate and can and expects to support any number of addresses on an interface. I could, and often do argue, that IPv6 will actually simplify a great many things once it's built out.
The compelling reason to do it is because you will have to do it anyway. It may come in a year. It may come in 5 years, but it will come.
I'm not a sysadmin and I have not used a windows box for more than RDP for VMWare or DWDM management software for almost 13 years, but I believe even XP is out of support. Those old boxes are a security or support incident waiting to happen.
What I'm getting at is that IPv6 is actually easy. It's not scary, it's not new. It's just different.
