For a business that sees no need to upgrade some perfectly good software that runs great on XP...... Keep those XP machines
But I would keep them off the internet due to security problems and prolly only old browser versions can be used due to the new far superior and secure versions of Firefox etc being too burdensome on XP
These small businesses could run XP (and their old reliable software) virtually on brand spankin new computers that would then be fine (secure) on the internet with Windows 7-8-10 etc. New desktops-laptops are cheap these days
An interesting suggestion, but I feel I must point out that you are overlooking the ‘driver’ problem. If the machine is fairly new, the manufacturers most assuredly did not bother to include any drivers for XP so it will have a hard time properly displaying on the monitor, not to mention the system bridge chips which control things like internal drives, sound, and networking to name just a few. Then there is the USB 3.0 standard which was not around when XP was first released. Add in SSDs and flash drives and one can only imagine some of the difficulties that would be encountered. :(