*snip*
XP can only use DirectX 9. Development APIs are currently at DirectX 11 but absolutely nothing is currently taking advantage of it because of Windows XP and the two consoles. XP can also only use Dual-Core Processors and up to 4 GB of RAM. Yes, that's still utilizing more than the consoles are capable of, but it's also ancient in terms of PC hardware where we're up to the most expensive gaming PCs coming equipped with 32 GB of RAM, dual-DirectX 11 GPUs, and quad/hex-core processors.
Mid-line gaming PCs tend to have DirectX 10/11, 6-8 GB of RAM, and a dual/quad-core processor. XP can't support any of that anymore. Yes, at the very minimum, XP would probably be just barely enough, because most processors aren't taken full advantage of anyway so a dual-core is still good for most games, and the GPU load can be eased greatly by changing around resolution and other options, but there's a point where that 4 GB limit is going to come back and bite XP, because PCs use significantly more RAM than consoles do.
Complaining that XP is losing support is like complaining that the PS2 has lost support. The PS2 was a great system, it lived long past its prime, and I'm sure people didn't want to "upgrade" from it when the PS3 first came out, but eventually people just stopped making games for it.