Yes it will be interesting to see what the response from Intel, AMD, ASUS etc will be. I don't think the technology is the challenge per say.
The fundamental challenge is that the PC market is made up of such a large number vendors which only make one part of the whole thing. All of these have too coordinate.
What accelerator/coprocessor should be added and supported? Intel, AMD, Microsoft, ASUS and many others may have to agree on this. I don't honestly know how consensus is built in the PC world.
The problem with adding coprocessors on the motherboard is that you will potentially get a bandwidth problem. OTOH that also allows you to add far more powerful coprocessor with higher power demand.
M1 can obviously not be compared to top of the line Nvidia GPUs. However M1 is for entry level Macs that cost less than a lot of these Nvidia cards.
The next M processors will get up to 32 high performance cores according to rumors. The GPU will go from, I think 8 cores today to 128 cores. With that many GPU cores, I think it is quite possible that Nvidia will get a run for the money.
Apple GPUs don't need to match an Nvidia GPU in raw theoretical performance to outcompete it. An Nvidia GPU will always be liimited by a slow PCIe bus, in ways an Apple GPU will not.
Ultimately I think the counter, would be that Intel and AMD begin to design their own SoC. But it will be messy, because where does that leave companies like MSI and ASUS?