How big threat do you think Intel ME is in reality, not in theory?
When it comes to Intel Management Engine, I actually think it's not a threat if you neutralize it. I mean to just set the HAP bit on it. Because if that isn't enough then that means all computers in the world which use Intel CPU can be accessed by NSA but if NSA had this much power then it seems obvious that they aren't using it and why wouldn't they use it?
There's a github project to neutralize/disbale Intel ME: https://github.com/corna/me_cleaner
Disable is overwriting intel ME as much as possible with zeros, leaving only a little remaining to be able to boot the computer.
The newer the intel chips are, the less likely it is to be able to disable it.
But all chip sets can be neutralized which means to set the HAP bit which is an official feature. In theory we can't actually trust the HAP bit to really disable intel ME permanently. It's more like asking Intel to do what they have promised because it's proprietary. But I think it really does permanently disable it because otherwise NSA would be abusing this power.
That's why I think the newer laptop models are better because it's probably not necessary to disable, it's enough to just neutralize withthe HAP bit. And with a newer modern laptop they can have open source Embedded Controller firmware which is better than proprietary Embedded Controller firmware.
I choose not to think about it or include it in my mental threat model, the same way I choose to not worry about thermonuclear warheads.
If there’s some exploitable backdoor and Intel gets owned, we’re all boned and there’s nothing we can really do about it. I don’t have anti-ballistic-missile systems, and I also don’t have the capability to make an entire hardware/firmware/os from scratch.
So instead focus on the things you can control and are more likely to happen. Don’t plan for doomsday, plan for every day.
I would go on eBay and buy a Libreboot machine from 2009 and prior (X200, T500, etc.) These systems have 100% no blobs in the firmware and can have the IME fully disabled. I use these as my daily and I'm fine.