It wouldn't be economically rational for Apple to bring down its own moat.
When they switched to x86, it didn't take long for them to release Boot Camp, so they could take Windows users' money, too.
How could that possibly disrupt their Software/Services infra?
I am not an Apple user. Do you _have_ to pay for iCloud if you buy the laptop? I don't think so.
Asahi-on-Mac would bring in irrelevant numbers for a company of Apple's size.
Sure they are probably thousands if not millions of (in the positive sense) nerds and geeks posting on HN about buying a Mac first hand, not second hand, solely to put Linux on it but even then would be a drop in the ocean compared to the remained sales.
Still if you have numbers on that I'd love to be wrong about it.
Amazon do the same with the fire.