As I recall, the first switch had the issue of the early PPC chips, 601, was kind of slow, and the boxes not designed well. The second transition in 2006 was annoying because Adobe doesn't like to rewrite their code... they carbonized, and then just kept charging for the same cruft. But frankly, I liked the Classic Environment, and I liked the first Rosetta. I'd like to run the whole shebang in MAME on whatever hw, if others were doing it to make it easier for me. If only MAME had a emulated coprocessor, I'd run A/UX on it.
Apple's current ARMs and OS running on it are already quite amazing, IMHO. So I don't think the new ARM Macs could disappoint. And the same thing here, Universal Binaries, a switch in the compiler to make it easy for devs, and I don't know how it could be easier.