Daniel,
If we're going to put the world thru the pain of change, it seems that we should do our best to ensure that it never, ever has to happen again.
That's the goal here? To ensure we'll never have another protocol transition? I hope you realize what a flawed statement that is. We can't see into the future. However, assuming that IPv6 is the Last Protocol seems a bit short sighted. If we get 20 years out of IPv6, that will be just peachy.
I see that as a worthy goal and no, I don't see that as flawed. While we certainly cannot guarantee that v6 will be the last protocol, we should certainly be designing for it to be the best that we can possibly make it. Just how many times do you think that we will replace all implementations? This change is simply fundamental to the way the Internet works. There is almost as much pain associated with this change as if we were to change the electric outlet voltage in every single country to a mutually incompatible standard. Can you imagine power companies making that change and then telling consumers to expect another such change in 20 years? To not even *attempt* to avoid future all-systems changes is nothing short of negligent, IMHO.
Of course, if we can't get PI address space for enterprises and real multihoming, there won't be any real IPv6 deployment. Lots of (possibly illegitimate) IPv4 trading and NAT, but not IPv6.
These aren't nice to haves. Even if it shortens the life of IPv6, that is an acceptable trade-off.
IPv6 is not the Last Protocol.
If you do get PI space for multihoming, then by definition, it cannot be the last protocol. In fact, it will have cemented v6's lifetime as just 10 more years. Tony