I agree that the registry is a dinosaur (I doubt you'll find anyone who doesn't agree). But I don't think the move to 64-bit provides a real opportunity to move beyond it. True, apps will need to be rewritten, but it's not like they'll need to be rewritten from scratch. Developers will want to use the same APIs, the same routines, and Microsoft wants to make that as easy as possible.
The same thing is true on the Mac side. When Leopard comes out, and we'll finally be able to make 64-bit Cocoa apps, we will not be switching to an entirely different API. The only things that will change are the internals of the Cocoa framework (meaning our code that uses the Cocoa framework will not need to be changed at all) and our own nitty-gritty number code (if even). It's similar to the transition to Intel in many cases, all that will be needed is a simple recompile. That makes for happy developers.
Similarly, 64-bit Windows apps will probably be using much of the same code to access the registry as their 32-bit counterparts. MS couldn't kill the registry without causing tons more work for developers (including themselves).
What MS could do is phase it out. Apple does this all the time. Take a look through their developer documentation, and you're bound to see routines that say "deprecated; use blah-blah-blah instead". In Tiger, for example, all of QuickDraw is deprecated. (QuickDraw is the graphics API that came from OS 9.) It still works, so developers that rely on it are not instantly screwed, but Apple has lit a small fire under their butts to encourage them to move to newer technology. The important thing is that Apple is NOT simply flipping a switch to kill the technology (and flipping a finger at the developers who use it). They're slowly phasing it out. When 10.6 comes out, it's possible they will remove a lot of these deprecated routines entirely. But by then, developers will have had time to update their code, and the number of people who rely on software that uses the old routines will have sharply decreased.
All Microsoft needs to do is establish alternatives to the registry, and encourage developers to start using them. Then in 10 years, they can pull the plug and most people won't even notice. It'd be sort of like how Apple moved away from the invisible type/creator codes of the classic Mac OS. Even today they still work, but most apps don't even use them, let alone rely on them.
But there's no way the registry is going away anytime soon. Microsoft is too committed to legacy support. Apple's switch from 9 to X was extreme, and it was painful. I really don't think MS could afford a similar switch. Apple did it because they didn't have all that much to lose.
