If it's crap ... We'll tell you
They're completely over-hyping the movie.
Don't get me wrong, I'm personally pumped to see The Hunger Games. At the same time, however, I've met several people who say they're not going to see this movie. On top of that, as the article mentions, the books don't sell nearly as well as Harry Potter or Twilight, so there's not as big of a fanbase.
My guess is that if the movie turns out great, it will turn out to be a success similar to How to Train Your Dragon, in which most of the crowd has no interest at first, but they'll hear about how great it is from those who do see it and go to see it in the following weeks. But a $100 million opening? In your dreams, Hollywood.
It will be a success but it's impossible to see it reach those numbers. And if it does, then call me a brain-dead monkey's uncle.
This article is full of mistakes so their speculations/expectations don't have to be taking too seriously.
And $155 million dollars later...