The xbox and the iPhone are the security models I expect on almost all mainstream computing devices soon. I estimate that it will be impossible or near impossible to execute any code that was not approved by the hardware vendor, and obtained by the hardware owner IDing themselves to the code distribution/signing service ("stores").
Anonymous software publishing or use/consumption will be relegated solely to what will, by then, be ancient and slow hardware, and relatively dangerous (for non-experts) OSes.
Modifying the signed apps or OS to remove their phone home and spying will be impossible, like iOS is today.
There is presently very little stopping large vendors from implementing this across the board, and, indeed, consumer demand for malware-free (but not vendor spyware-free) platforms is driving this in a big way.
Already every mac available for purchase, even the Intel ones, requires online activation to wipe and reinstall the storage:
https://sneak.berlin/20201204/on-trusting-macintosh-hardware...
I imagine this will happen regardless of ISA; see what happened with the intel ME and related DRM, and Pixelbooks/T2 macs.
Most people buying computers don't want flexibility, they want reliability. OS alternatives, software alternatives, and privacy aren't really part of the buying decision outside of a small and mostly commercially irrelevant market segment.
The e-waste will be colossal when the vendors just decide to EoL them. You won't be able to reinstall the OS on any current Apple product (phone, tablet, or computer) once Apple's activation servers for those devices go offline in 10-20 years.