^^^^ I've been on since '84, same transitions (and still have to fire up my Mac Pro G5 Quad here and there, for one thing—dang that thing is loud and warm).
But don't forget that in the previous two changes, the Mac's CPU had fallen behind the competition, PCs. More precisely, in the first case, purely behind in processing power, and for the second it was a processing power per watt issue—G5 was a great floating point machine for the time. But especially Apple's lucrative laptop business. Apple absolutely had to ditch those processors quickly, across the board. A time frame like 2-3 years could have been fatal, as they'd be so far behind the market in that time.
This is a little different in that the processor Apple's moving away from is shared by the competition, and they aren't going anywhere. (Someone might bring up AMD, but you know what I'm saying—you don't quickly fall behind the market staying on Intel.)
We'll see how fast Apple moves, but I'm just saying the motivation is a little different this time. I expect Apple to move aggressively for lower-end laptops to start, iMac—the higher unit sales items first, to a lower-end market that will tolerate the typical applications and not miss the high-end ones. By the time they get to the high end units, the high-end, specialized applications will be there.
BTW, I did say Apple would absolutely have to have a "Rosetta" for ARM, so I got that right at least.