My suspicion is that he simply might spend some time with his newborn and enjoy life a bit after such a wild streak. He has more than enough financial resources to do that comfortably.
He has stressed twice in the post that most of his life revolved around that company - Maybe it's time for that not to be anymore - simply put.
Doubt there's anything sinister or shady about that. Maybe he doesn't have any plans. Or maybe he just doesn't feel like sharing those plans or doesn't feel obliged to share them.
My guess (could be wrong): He no longer enjoy writing Go.
He's been working hard on a really cool modern terminal emulator the last couple years, among other things I'm sure.