It was at banned at PPUSA this year, and I, quite frankly, could not have been happier. Moshing is retarded. Nothing like having a 450 lb guy try to get into it to remind you "hey, I could get seriously fucking hurt".
I've been in the pit at Slayer - it was my first and last time in a pit.
They're not going to ban concerts, especially not over a freak tragedy such as the one at this AC/DC show. Will they overreact? Maybe. But this is Australia, not Saudi Arabia.