Well, lets take a look at Windows 7 for a minute. Microsoft put it on extended life support (for corporations) and does not support it anymore.
There are still 'some' Win 7 (and xt) computers still running either off grid or for people who have legacy programs that they have not taken the time to replace. Many people are moving to Windows 10 because there are replacements for the older programs and Windows 10 does it more efficiently (saves steps). A voluntary act.
So, it is not likely someone will come to your door to collect or 'bin' your device. It simply won't be as useful as the newer devices.
Communication speeds are improving as well as response times. The older a piece of hardware gets it becomes harder for it to be updated and for it to keep up or be compatible.
Security is yet another issue that is reason to update. Some older hardware will be hard to update due to constraints. You can add new boards and modules on a PC but that is not an option for most laptops (it really pays to go over the specs on those).
More than likely the reason you might want to upgrade is for a better experience or maybe the hardware will just quit. Some devices are just not repairable...
I recognize that some very old hardware may not perform well on newer software versions.
What bothers me, is that two years ago I buy a laptop with above average features, pay a small fortune and it is still better than many computers sold today.
Now, Microsoft comes along and says that my processor does not meet the minimum requirements and worse, says that a current Atom processor is compatible.
In any decent comparison, an Atom of the current generation will never have the performance of an I7 processor, even if it is a 7th generation one.