But whether you internetwork with IPv6 and NAT, or just keep IPv4, NAT will not go likely go away.
Directly internetworking IPv4 and IPv6 (where an IPv4-only host talks to an IPv6-only host) is only possible for IPv6 hosts that use an IPv4-compatible address. This is an interesting experiment, but it's not very useful as this imports all the IPv4 address-related issues into IPv6.
The "math" below works out because 9 billion people don't each need a unique IP address. The vast majority of those people will be serviced via NAT,
What is your basis for this argument? The current host count is around 250 million but there are 2 billion addresses in (some form of) use. This is obviously going to get better and in the long run not every individual needs a public address 24/7, but I don't see how we can get from 5 - 10 addresses per person to 0.3 without significant problems.
as cable and dsl providers are starting to do now.
I don't know which part of the world you hang out, but I've never seen any ISP NAT on behalf of its customers. I've heard some talk of GPRS service providers doing this (but not seen it) but certainly not broadband or regular dial-up. If there is NAT somewhere, it's done by the end-users themselves.
The other problem is that the entire world can't be converted at once, so
there is significant business in the IPv4 side, that the IPv6 side can't
abandon or lose connectivity to.
So? One way to accomplish this is to install IPv6 everywhere and only keep a few gateways around for access to "legacy" IPv4 web, email and the like.
It would be like losing the ability to contact your bank and make deposits
if you upgrade to the new version of the accounting software. You can't
do that. And the bank can't upgrade because then it would lose the people
who haven't upgraded.
Way back when I had to use special software to interact with my bank, I used to get a disk with new software in the mail several times each year. I guess switching to a web based system was worth it for them because of the savings on postage alone.
Thus, legacy software is frozen in place, until it
is no longer useful. This is why most of the software written, is still
written in Cobol. It is likely that Cobol, and IPv4 will still be in use
in 2050.
That's ridiculous. None of us used IPv4 46 years ago, there is no telling what we'll be doing in another 46 years.
I think IPv6 would get faster deployment if the cost structure of IPv6
address space were different (free, or $35/yr registration fee), and one
tried to get a specific new industry to adopt it like a proprietary
protocol that just isn't propietary. My company, Av8 Internet, doesn't
have IPv6 address space because it costs too much money
Talk to ARIN. Here in Europe there is no additional cost for ISPs to get IPv6 address space.
for a plaything, and for many years to come, it is just for play.
Unless you are a hardware or software vendor and your customers want IPv6.
You observation that IPv6 is more than just expanded address space is
good, but when given the chance to create a new protocol, people put all
kinds of improvements in. These improvements increase the complexity
somewhat, but I'm not sure they change the overall problem very much.
Given the cost of the change, one would kind of want some significant
improvement besides address space.
What would this cost be? Are Windows XP and MacOS Panther more expensive with IPv6 support than without? (You don't need IPv6-capable routers or switches in order to run IPv6.) And IPv6 is still IP, it's not hard to learn.
Now if people prefer to stay with IPv4. that's fine. But the people who made IPv6 happen deserve some credit because if and when the time comes that we really need IPv6, it will be there, which is a very comforting thought.