Chromebooks are useful, but heretofore, Google only supported them for a few years. Going forward, all Chromebooks will have a minimum support lifespan of a decade.
Starting next year, Google will provide Chromebook security patches and software upgrades for up to a decade. This will effectively guarantee that no existing Chromebook will expire within the next two years.
However, a Google spokesperson added the caveat that, "In making changes to the expiration policy, we have to coordinate with each partner making any component in these devices. It requires a security and performance guarantee from the makers." Other Google sources indicated that the major Chromebook vendors are expected to work with the company to extend their hardware's lifespan.
Good luck getting a web browser to launch on a 10 year old chromebook. Most of them are built with the cheapest hardware possible and web browsers keep getting more bloated with every feature added.
Even for x86 it depends. Often they're built like Android devices and they have weird hardware that isn't properly supported by kernel.org Linux. My prematurely end-of-life Chromebook has problems with sound and thermals and longevity when running regular Linux. I replaced it with a laptop that has official Linux support. The build quality to price value is worse, but it's not hobbled by inconsistent, half-hearted hardware support over an artificially limited lifetime. Even before it was end-of-life, my premium Google Chromebook had to wait to receive software features that were available on newer Chromebooks because the drivers weren't compatible with new kernel versions.