It's bittersweet for me. I grew up with id games and John Carmack has just always been there as id's genius programmer guy. Feels like the end of an era.
On the other hand, John Carmack is working full time for Oculus VR!
This is extremely good news. There's only so much one person can do to push forward 3D rendering engines, and no doubt he's done a lot in this regard. It's diminishing returns now. The engines look fantastic, and you have a choice between Unity, Unreal, Source, and the various Quake-derived ones.
There's a lot of low-hanging fruit in the VR world, plus tough problems to solve. Carmack will be at home here.
About 10 years ago he talked to some of us guys writing 3D drivers for Linux, he is all kinds of awesome when it comes to code skills and spent a few hours geeking out with us at Siggraph. About a year before, I got to see his coding in action when we were first bringing up the first Matrox G200-GLX driver. He would accomplish so much in just a few days when he donated some time to helping us get the MGA-G200 working with Quake. He would accomplish in days what most of us at the time would have taken weeks to do. He just naturally understands 3D and 3D hardware and is a geeks geek. I will bet he is spending most of his day to day coding and hacking.
I should add that I hope we haven't seen the last of his Code God skills. The title of "CTO" kind of scares me in that regard, unless, of course, Oculus is still small enough that the CTO might still be expected to put his hands in the source.
On the other hand, John Carmack is working full time for Oculus VR!