I'm not sure hitting a concrete wall at that speed would have been survivable.
It depends, since the car was traveling sideways and not just directly into the wall the impact would have then slid the car down the concrete barrier. He likely would have punched the nose in, then the car would spin around backwards slamming the left side tires into the barrier and then possibly coming around again with the rear end against the wall.
What would not have happened was having the car ripped completely in two and exploding in a fireball. If RG had been knocked unconscious he would have burned to death, if he passed out from the impact with a concrete barrier he would still have made it. It was awesome that the medical car was so close, and those guys are heros for rushing that fire..........but bottom line they didn't get RG out of the car, he did that himself. If he hadn't been able to do that it wouldn't have mattered how close they were.
I'm just saying, F1 cars have not burst into flames in accidents for decades, to have one do so now solely because of contact with a safety barrier means that barrier is not actually safe.