I almost missed it, but he announced it at the end of this recent video: https://youtu.be/-9cW4Gcn5WY?t=2720
I used to be a CS grad student at UofT, where if you ran `finger hinton`, you'd find out that Geoff's "plan" was to figure out how the brain works. No surprise there. But if you then also fingered Hector Levesque, you'd see that his plan was to (paraphrased) "wait for Geoff to figure out how the brain works and then apply transitivity". Hector was on my thesis committee and I was in his camp in terms of waiting and transitivity -- mostly because I couldn't contribute much to the former. That quote inspired me so much, I named my company after it (Transitive Robotics).
But now the plan is broken -- at least superficially. Was I the only one missing this news until now? I'm surprised there wasn't more talk about it. Are people not saddened by this? I am.