I'm not sure why you say that, rollovers in collisions between two sedans, even at those speeds and angles are extremely uncommon.
I'm really glad the OP is okay. The person who hit them is an extremely irresponsible person. This looks like a combination of distracted driving as well as someone who was driving uninsured.
The cops aren't going to do squat about it even with the damning dash cam video. They've got bigger fish to fry like writing tickets for people going 10mph over the speed limit. Because everyone "walked away" this is really no big deal to them. Speaking from experience when my wife was rear-ended by a driver with no insurance and no license and the cops just didn't care about it.
OP insurance company might go after them through wage garnishment or other legal means considering the size of this claim. However the OP might best be served by retaining their own lawyer and suing the owner of the vehicle... who, I guess, if they are smart will claim the car was stolen.
This is also why we carry a 2M umbrella and I really urge everyone to have one. We could loan our car to someone and they could do something like this that results in a major tragedy that would go out of scope of our regular coverage.