They're now saying that his helmet was cracked open, and they estimate that he was doing something around 50mph at the time of the accident (which is extremely fast for recreational skiing). There's also been photos and video in the media of the apparent area in which he was skiing. It's absolutely littered with rocks and outcrops.
It goes without saying that I wish him well, and wish for a full recovery (as I would for anyone - famous or not - who received such injuries). But I also have the opinion that an experienced and highly competent skier (as he was), who elected to ski at such apparent speed through such dangerous terrain, is electing to take a significant risk with his wellbeing (and his life). If he didn't want to put his life and health in anywhere near as much potential danger, he should have been skiing slower, or skiing fast on prepared slopes. It was his decision to make.
The hospital press conference going on right now seems broadly positive, in that the bleed and swelling seems to be under control. It will still be near-impossible, however, to know the true nature of the insult to his brain until and unless he is brought out of artificial coma. There seems to be a suggestion that the brain was a) physically torn and contused, and b) subjected to such subdural pressure that there's a real possibility of ischaemia (damage from insufficient supply of oxygenated blood). Only time will tell......