You are making it sound far harder than it really is for Apple. They probably have Mac OS running on ARM for a few years.
Holy balls, I don't think you know how to read.
I've said at least three times now that anything Apple would need to do is very, very easy. It's the third-party stuff that's the most difficult part of the transition.
Christ on sale.
You may not have been around for the PPC to Intel transition. I was. And getting developers to write native apps and stop depending on Rosetta was like pulling teeth.