There is no upgrade path from XP. Those boxes were built to run with as little as 512 MB of RAM, if not even less. They have slow processors that won't run Win7 or later. I know because I dealt with this before, and I have a few of those boxes now. The only upgrade path that they have, in theory, is Linux; but in practice they have only the path into dumpster because it costs you too much to upgrade them and to use them, compared to buying a new system.
The real problem is with XP that operates equipment. Here is an example:
This particular, now obsolete, oscilloscope was sold for about $25K then, and it still is a perfectly good instrument today. It is selling right now from $5K to $10K. But it is controlled by WinXP. If you have ten of those oscilloscopes in your business, would you be in any hurry to scrap a quarter million dollars in working hardware just because of a very remote threat? Those scopes have never seen a Windows Update in their life, by the way - you cannot risk that on a soft real time equipment. If you have to protect them, you do that with firewalls; but most scopes are not even connected to the network. Maybe GPIB; but Ethernet at that time was not very useful.
This is not the highest price for a unit of equipment either. Take this signal source analyzer, for example - its price can be above $60K:
There are CNC machining centers and robots, however, that cost far more than that. The fact is that XP/XPe was a de-facto standard for all such equipment for ten years. All high-end, smart equipment made in the last decade runs XP. There is no way to upgrade it. Discarding it would cause terrible financial losses, and it would be also not very wise because the hardware still works fine. So XP will soldier on.