"the way to force the remaining people to update is to just forget it"
I disagree. People moved in droves off of NS3 to NS4 (no longer requiring us to code for it)because it was better. People haven't moved in droves to NS6 because it sucks, and 7 is worse. The answer is not to forget these users, it is to give them something better.
I'm using Mozilla. Not because it's better than anything else. To me the only thing it does better than NS4 is crashes more reliably, more often, and more spectacularly oh, and it renders a couple pages better. But it renders a lot of pages worse too. Why do I use it? Because it runs exactly the same on everything I use as an Operating System. That's it.
So if I wasn't in a place where I use so many O/Ses I'd still stay with NS4. I haven't seen anything that much better. Modern skin. big whoopdy do. Standards. Yup. Todays standard is by the w3c. Tomorrow's standard is "IE does it, we need to do it that way too". Yesterday's was "this embedder says we need to do this". It doesn't feel faster(except deeply nested tables). It isn't any easier to use. No new features I really care at all about except tabbed browsing. It's full of geeky stuff I don't care about. DOM inspector? So what?
Sorry man, I just don't see that ignoring someone is the answer. Give them something better to use, and thus far AOL/Time Werner/Netscape isn't doing that. To me, neither is the competition.