Why would iTunes need to be 64 bit? Exactly how much memory should iTunes need to address?
Remember, being 64 bit does not mean the program will run faster and have new features. At this point, running a 32 bit app on a 64 bit OS isn't gonna slow your system down. If it ain't broke, don't break your back to fix it. Eventually, it will probably migrate to 64 bit, but that, in and of itself, will not make it more stable or faster.