I doubt the lawsuit will get any traction. F1 has very deep pockets and as this was also a safety issue they had a responsibility to keep spectators safe. I read that they are only seeking $30,000 in damages, which is peanuts to F1, but they will fight this on principal.
EDIT: $30,0000 per spectator. ~$1B for the 35,000 present.
The race itself was actually pretty entertaining. Even the drivers commented that the racing was better than they had anticipated. I could have done with less spectacle though. Being Vegas, I knew ahead of time that everything was going to be over the top but eventually even the best commentators run out of meaningful things to say. Well, better get used to it because it's a 10 year deal.