I think concerns about how Apple will handle the transition can generally be addressed by the relatively smooth transition from PPC to Intel. Apple has literally done this before.
Apple transitions CPU architectures every 10-15 years.
6502 -> 68k in 1984 via hard-cutover [edit: see cestith's reply, there's more to this story than I knew]
68k -> PPC in 1994 via emulation
PPC -> x86 in 2006 via Rosetta JIT translation
x86 -> ARM in 2020 via Rosetta 2 static recompilation
You could even argue the transition from Mac OS 9 to Mac OS X was a transition of similar magnitude (although solely on PowerPC processors), with Classic Environment running a full Mac OS 9 instance [1]
I disagree that 6502 -> 68k was a "transition." The Apple II and Mac were two separate product lines. The three major early home computer companies (Apple, Atari, Commodore) all did this.
This is true, but note it was released in 1991, many years after the Mac's introduction. By that time, the Apple II was definitely on the way out. The last hold outs (schools...) probably needed encouragement.
Yes, in 8-bit mode. The IIgs runs with the processor in 16-bit mode from everything I've read about it. It might be able to swap modes to run older Apple software, but the IIgs is a 16-bit machine.
Correct me if I'm wrong, but I think they also didn't announce any actual hardware when they introduced Intel Macs.
Interestingly, for the PowerPC->Intel transition, they also had an Developer Transition Kit: https://www.macstories.net/stories/this-is-not-a-product-the...