Actually that's the planned idea, that when "win9" rolls out that's the "eol" for 32bit. Much like with Win9x was the "eol" for 16bit, outside of specialized emulation. Whether a processor supports code execution is different from the OS supporting the execution of the code in a protected environment as you should know. Much like 8bit in a protected environment. And sadly, I have too much experience in making legacy 8-bit hardware and software work in modern machines. It's somewhere between, make it stop and this is the 9th level of hell.
And, in general 32 to 64 bit isn't "flipping a switch" unless you're enabling the handling of larger memory addresses. Which is something you should already know, not forgetting that in 64bit that you're usually doubling the size of your handlers in most cases. Not always but most of the time. Anyway, if you've been paying attention to what's been coming out of not only MS, but from the 'nix camp for the last several years the days of releasing 32bit OS's are pretty close to being dead in the water.