You've might already read it on the Gentoo news site, the Hardened Linux kernel sources
are removed from the tree due to the grsecurity change where the grsecurity
Linux kernel patches are no longer provided for free. The decision was made due to
supportability and maintainability reasons.
That doesn't mean that users who want to stick with the grsecurity related hardening
features are left alone. Agostino Sarubbo has started providing sys-kernel/grsecurity-sources
for the users who want to stick with it, as it is based on minipli's unofficial patchset.
I seriously hope that the patchset will continue to be maintained and, who knows, even evolve further.
Personally though, I'm switching to the Gentoo sources, and stick with SELinux as one of the
protection measures. And with that, I might even start using my NVidia graphics card a bit more,
as that one hasn't been touched in several years (I have an Optimus-capable setup with both an
Intel integrated graphics card and an NVidia one, but all attempts to use nouveau for the one game
I like to play - minecraft - didn't work out that well).