You just have to look at the phone community (XDA Developers, etc) to see how this will (eventually) go.
A good example were the old Asus Transformer tablets. They were a super niche device, but it still lended itself to Linux and so a small team of people managed to load Ubuntu on it.
Another are Samsung phones. They try to lock people out, but they have popular enough devices that people find a way to put LineageOS on them.
Finally, even iPhones aren't immune. Small teams of people have managed to load Android on them and get it (partially) working. More people would give them even greater functionality.
If laptop manufacturers lock things down with ARM, there will be people who work around those mitigations and install their own OS on that hardware. Tooling will be developed to make that process easier and easier for the next round of people with that device (or future devices). It'll suck up front until the community grows large enough to work around issues faster and faster.
And that's even supposing worst case scenario. I'm not fully buying the idea that you _won't_ be able to change the OS on these laptops. Microsoft has tried (and failed) to lock other OS's out of their laptops. Chromebooks are (currently) the largest market of ARM laptops and you're able to change the OS on them. Apple might be the only company even remotely able to hinder freedom on their devices.
Either way. In the war on general computing, I'm generally optimistic for the users.
That's actually quite a depressing look - while the community can often get undocumented & closed user hostile hardware run their OS of choice, it's hardly ever as seamless as installing a modern Linux distro on about anything x86, usually without issues - mostly thanks to standards such as BIOS/UEFI, ACPI & others.
Also even if you liberate a single device, it does not mean all your hack will work on the next one - it's a never ending battle. And without making sure manufacturers actually respect some standards such as they do on x86, it might become a loosing battle long term...
Sure, the lockdown situation is worse than things are currently. You're likely to need per-device hacks that unlock it and enable freedom for users.
Even in that scenario though, ARM devices use standards too. There's a reason I can generally pick up any Android device and know what needs to be done to build my own OS for it. We just lack tooling that makes that incredibly easy and lack maintainers who want to make those devices work with the mainstream linux kernel.
Having open devices though (outside of Apple) is still my bet. We still need to make that process smoother but that just means there's lots of low hanging fruit :)
Still I don't see this scaling unless more of the ARM stuff is standardized or upstreamed by manufacturers - IMHO there is simply not enough OSS developers being both willing and able to do the often menial yet necessary platform adaptation work.
For that reason I'm morehopeful about built-to-be-open hardware like the Pine Phone, as that could help reducing or removing the device support treadmill, so useful features can be actually developed. :)
A good example were the old Asus Transformer tablets. They were a super niche device, but it still lended itself to Linux and so a small team of people managed to load Ubuntu on it.
Another are Samsung phones. They try to lock people out, but they have popular enough devices that people find a way to put LineageOS on them.
Finally, even iPhones aren't immune. Small teams of people have managed to load Android on them and get it (partially) working. More people would give them even greater functionality.
If laptop manufacturers lock things down with ARM, there will be people who work around those mitigations and install their own OS on that hardware. Tooling will be developed to make that process easier and easier for the next round of people with that device (or future devices). It'll suck up front until the community grows large enough to work around issues faster and faster.
And that's even supposing worst case scenario. I'm not fully buying the idea that you _won't_ be able to change the OS on these laptops. Microsoft has tried (and failed) to lock other OS's out of their laptops. Chromebooks are (currently) the largest market of ARM laptops and you're able to change the OS on them. Apple might be the only company even remotely able to hinder freedom on their devices.
Either way. In the war on general computing, I'm generally optimistic for the users.