The nvidia-173xx and nvidia-96xx driver packages have been removed from our repositories as they are incompatible with newer xorg servers. This can only be fixed by an upstream update, which has not happened yet.
For most video cards, the best alternative should be xf86-video-nouveau; see: https://wiki.archlinux.org/index.php/Nouveau
As lower-grade options, you might also consider xf86-video-nv and xf86-video-vesa: simply remove the old nvidia driver(s), install these, and the xorg server will automatically pick the best at startup.