I read the SI article - that's pretty vague and basically irresponsible reporting. It doesn't actually say anything. It's hard to really figure out what's going on from these scattered reports, but it's pretty easy to figure out he has a bad injury. Ending up in a persitive vegetative state is pretty rare, most people improve past that, or die. I think at this point there are two possibilities. Either he still has elevated intracranial pressure and they are keeping him down to control the pressure or his pressure isn't a problem anymore but he isn't waking up. The latter carries a worse prognosis and implies a brain stem level injury. I've kept people in an induced coma for over 2 weeks, so that in itself isn't that unusual, but it does imply a pretty bad injury. I think all we can say at this point is that if he survives he has a long road ahead.
I think it goes without saying that we all hope he makes a good recovery. He certainly was an interesting guy to watch race. His work in the rain was some of the best ever, and his his fake crash during Monaco qualifying was a baffling dick move (among many others).