Keep in mind that’s only the user mode portion of it. The kernel mode portion is entirely absent from Win7, so performance won’t be as good as Win10. In fact it’s unlikely to offer a performance increase over DX11 at all, especially on NVidia hardware.
The idea is to allow the API to work at all for titles which may not support DX11 (or may not offer their whole feature set when doing so, despite the existence of FL11_3), rather than to increase performance.
Extended support for Windows XP ended 5 years after the end of mainstream support, just like Windows 2000 before it and Windows Vista after it. Mainstream support for Windows 7 ended in 2015, and I don’t see any reason why extended support would not end 5 years later like the previous 3 versions of Windows (NT).
Windows 7 was so good… I wish Windows 10 had a switch that could be flipped that put it into a “7 mode” or even “XP mode” of sorts that disables all the new fluffy crap that’s accumulated over the years. I use my Windows install as a high-powered game console (dual boot) and as such don’t benefit at all from any of the UI changes or added bloat. I just need the OS to launch my game and go away.
Microsoft won’t extend Win 7 end of life. Not for free anyway. They already have plans in place to charge $$$ for extended support. Avaricious corporations now roam (and rule) the planet.