4. Nearing 2015, ISP wants to ensure its users can reach all the services in Internet, and deploys a v4-to-v6 NATIs it a given that NAT is the appropriate option in this case? Many protocols support proxies, where the name-to-address translation happens at the proxy so if the proxy supports IPv6, the client doesn't have to. (I don't think it's a good idea to mention dates, though. It's only recently that people have stopped whining "you IETF guys said we'd be out of IPv6 addresses by 2005 and it didn't happen".)Maybe I should have used s/NAT/translator/, that was certainly the intent. However, in practise given that the intent is to support weird v4 hosts and apps in "end-game" situation, it seems improbable that an app-specific proxying would be enough. Wrt dates, I wanted to emphasize that this won't be happening any time soon.
Given the rate that Operating systems are being forced on end users, what is the likelihood that non-dual stack systems will be very common by that point? I can see a need to take v6 customers to v4 servers, but I do not expect that you will have a large percent of users on v4 only hardware or operating systems 7 years from now. Now you may have v4 only ISPs or other businesses providing services but that is a different issue.
I expect once the IPv6 ball gets rolling people will start turning off IPv4 surprisingly fast.Personally I doubt it -- a lot. Or we have a different things in mind when we talk about "IPv6 ball gets rolling". I wouldn't turn off v4 on any service I have association with until at least 90% and hopefully more than 99% of the user base (or potential user base) could reach it.
This makes senses
Eric