After removing media-video/nvidia-kernel, media-video/nvidia-glx and installing x11-drivers/nvidia-drivers, in emerge -vauD world, x11-base/xorg-x11-7.0-r1 still wants nvidia-kernel/glx, don't accept nvidia-drivers as replacement.
Not x11-base/xorg-x11-7.0-r1, read the ebuild. p.mask nvidia-glx and find what really depends on it.