Switching to another chip would require a whole new round of rebuilding, or "porting," existing applications to work on the other chip. Here is the real danger for Apple, and the reason they won't switch chips.
If you're a software developer, and you're going to develop for an "Apple/Intel" architecture, also developing a "Windows/Intel" version is going to look pretty tempting. After all, you've done most of the work when you did the initial "Apple/Intel" port. That huge windows market is going to look pretty tempting.
If Apple's applications do start showing up in Windows versions, it will hurt Apples sales. Apples not going to do anything to make it easier to develop apps that run on Windows.
" If you're a software developer, and you're going to develop for an "Apple/Intel" architecture, also developing a "Windows/Intel" version is going to look pretty tempting. After all, you've done most of the work when you did the initial "Apple/Intel" port. That huge windows market is going to look pretty tempting"
Except there's nothing to leverage in writing a windows port. Presumably, if they released MacOS on Intel they'd have cross compilers and all sorts of tools to handle all the endian issues and whatnot for you. You're still writing to the MacOS API.
The Windows API is *nothing* like the Mac. I imagine it would be fairly painless to write a MacOS program that would run on either platform (given good tools), but having an Intel version of MacOS won't make a Windows port any easier.