Lets put it in perspective. If it launches at $600 in AUSTRALIA, it is still cheaper than PS3 Launch here of $1000. A damn ipad2 here is about $600-$800 depending on model.
Considering a lot of people are willing to spend that money on ipads here, then I do not see much of an issue selling for so high till launch of ps4/720.
I reckon launch price in the USA will be $350-$450 with a core game.