Who would want Windows 98 today ? XP is quickly fading away in the past, just the same way. At one point no end user will want to run it anymore.
Sure, there will still be dedicated solutions such as POS or ATM Machines that came prepackaged with XP, but those will never run anything but their original program, and cannot be considered desktop or laptop computers.
It is nobody's fault, but technical evolution is what it is. In the case of Windows XP, it could not do the kind of things that Windows 7 managed, and does not support most of the high end software available today. It is bound to go no matter what.
For most developers, it has ceased to be a worthwhile target. Of course, they will always remain some idiosyncrasies..