I think everyone remembers how slow DirectX 10 adoption was (and still is, as even some new games are DirectX 9 based), so there's nothing to say that if DirectX 12 is Windows 8.1 (or 8.1 Upgrade 1) exclusive that developers will take the time to code for it.
back when I was using this box I had DirectX 10 available
the 8600 gt had 32 CUDA cores, which is not very powerful compared to the GTX 660 Ti I am using now
that card is shader 4 compatible but had only 256 MB of VRAM which limited its ability beyond 1280x1024 panels
that card and the motherboard are both dead thanks to dodgy drivers