It’d be nice but it’s hard to say or do realistically. A major advance or lack thereof or the rise or fall of a competitor can change the landscape dramatically pretty much over night.

As a general rule think 3 year refresh cycle on a mid-level system for laptop/desktop or 2 year for phone/tablet. Of course there are many ways to extend that indefinitely depending on your resources what you want to do with it so “unusable” becomes very much a moving target. Unsupported tends to earn you an extra 1–2 years on many systems but at that point you need to pay attention to reqs and again it comes down to what functionality you expect.

No.

How would this work exactly? Take a notebook computer. The lifespan for the device will depend on a number of variables, such as the intended use. The near infinite combinations of hardware components means also means that this particular configuration will have a longer or shorter lifespan than other configurations of the same product. And the same laptop configuration’s lifespan will be different based on the time within the industry cycle that it’s purchased.

There are way too many variables for this to even come close to being possible – or desirable.

My rule of thumb is three years for most things. In other words, by the time the Lithium-ion battery has degraded, a portable device has been deprecated to obsolescence. As for desktop computers, it really depends on how much you spend. The average PC will be marginally adequate at three years and hopelessly obsolete at five, while high-end systems will be average in two years, adequate to about four or five, and obsolete around six or seven… but free people spend $3000+ just on their tower. Macs fare a bit worse as they already use a lot of last-gen components, so consider them average in this context despite coding the same as a high-end PC.

So far, I have not found any exceptions to that rule except for my old HP 48G calculator; I bought it in ‘96 and it’s still better than many far newer calculators.

What @tom_g said.
Things break and wear out at different rates and sometimes have glitches that cause breakdown. Just like cars. One may go 250k miles with no issues and another may flatline at 60K.

Shit, man. Fucking life should come with guarantees and warrantees.

It doesn’t, though.

They do. They call it the warranty period. Today’s products are designed to break.