It is inevitable. I guarantee you there will be people who run Linux on their silicon Macs. I don’t know how you could possibly hold a stance that no one ever will.
Apple is very hostile to it. It won’t stop everyone though. It’ll continue to be niche but it’s happening.
It's not inevitable. It's fragile. Go boot up your old iPad; that should be well-studied, right? We ought to know how to boot into Linux on an ARM machine that old, it's only fair.
Except, you can't. The bootloader is the same iBoot process that your Apple Silicon machine uses, with mitigations to prevent unsigned OSes or persistent coldboot. All the Cydia exploits in the world won't put Linux back on the menu for iPhone or iPad users. And the same thing could happen to your Mac with an OTA update.
It is entirely possible for Apple to lock down the devices further. There's no guarantee they won't.