The short answer is that no, I wouldn't upgrade my Mac simply because a new processor architecture were released. If anything, that would be even more reason to hold off on an upgrade for a bit longer, just to let the dust settle.
The longer answer is that, in the long run, it would influence whether I stay with Macs or not. I don't doubt that Apple could do some interesting things with their mobile computers by changing to ARM, but the desktops are less clear to me. I also don't buy the idea that Apple has been neglecting the Mac lineup because of Intel. I'm sure Intel has made things a bit more difficult for Apple, but I wouldn't be among those who inevitably cheer the idea of Apple returning focus to the Macs with an architecture change.
If the processing power were the same or greater that's all good and fine, but what does this mean for software availability? The discussion about third-party software was all good and fine but many of us are using professional software from companies that also cater to Windows. The Mac market share is probably fairly minimal for many of them; how many would continue Mac support on an entirely new architecture? I think a lot of people may be taking for granted just how much software became available on Macs when the transition to x86 occurred. I don't buy that distribution has become easier, otherwise Microsoft wouldn't have had to dump their ARM-based Surface a few years ago, and they'd probably be offering an ARM-based model now.
Someone earlier already said it best: Apple always charged high costs for their stuff, but it was justifiable. Now they're allowing their hardware to become outdated while maintaining the same pricing structure, which is quickly becoming laughable. If this architecture change causes pain on the software side and doesn't make a really good case for the user, I'm out. And once the computer is running Windows only, the benefit of having all of the other Apple products - iPhone, iPad, Watch, TV - becomes greatly diminished, and I might start looking elsewhere when those products need upgrades, too. I like my Macs and I like the overall Apple product experience, so I don't look forward to the possibility of going back to Windows... but Apple had better make this decision very, very carefully.