Assuming that Apple can get their chip up to the performance level of an Intel chip, this will be the end of the Hackintosh. With that being said, I've been a Mac guy for a long time. I remember the 68k-PPC transition, as well as the PPC-Intel transition. There will be some growing pains with the transitions (though I imagine fewer growing pains than with the past two transitions).
Intel started selling the first Intel Macs on January 10th of 2006. They shuttered production of the PPC macs that same year with the Mac Pro being the last model to be discontinued in August of the same year. Apple did not introduce the first Intel only version of OS X until 10.6 Snow Leopard in August of 2009. Even after Snow Leopard was introduced, Apple supported 10.5 Leopard until June of 2011, and the PPC versions of Safari and iTunes until sometime in 2012.
As I'm sure many of you know, in general Apple seems to support hardware for about 5 years after the end of sale. There is no official date revealed by Apple, so you have to go by when security updates stop happening. I was shocked that Apple supported the PPC Macs for so long, even after software developers had effectively abandoned them.
It looks like this rollout is going to be a slow go. Aside from the issue of RAM limits with the SoC, I just don't think they have anything internal that can match what Intel can do on the pro side of things. Even if the Apple Silicon starts to match the top tier Intel chips, everyone is forgetting that the Mac Pro is a thing not because of its "blistering" performance (yes, I realize the performance isn't so blistering), but because of its expansion capabilities. There are professionals using the Mac Pro who have populated every PCIe slot. Do Apple's SoCs even have the ability to support that much PCIe expansion?
Yes, eventually this will end the Hackintosh, but I'm willing to bet we're going to have at least 3-5 years after the last Intel Mac is discontinued. Of course, there is a possibility that somehow Apple could manage to kill the Hackintosh with their "T" security chips, but we haven't seen that yet.