I'm happy to provide some of my reasoning, though I readily accept the fact that my predication is very speculative. Much of it is based on the trajectory of the musical.
DEH came out of nowhere to become a smash hit, meaning there was no source material for the show whatsoever. Why?
For one thing, it told a compelling, and to many, a controversial story, a story that resonated across a very wide demographic, from adolescents through their grandparents, and a story that produced very emotional reactions. To some, Evan was a hero, for others, he was somewhat of a villain, and to most there was some of both in what was a very complex character. (The authors have discussed, in detail, that this was a deliberate choice on their part, they understood both sides of the argument). But the result of it was that people TALKED about it far and wide. It generated discussion and debate.
Another obvious reason is that it has a great score, and it's just entertaining.
And of course, they show got great reviews, went on to receive the Best Musical Tony.
So why won't these same things translate to the film? By and large, I think they will, though I have no idea at all how critics will react to it, because I think some will go into it looking for blood to spill.
So in a nutshell, those are some of my reasons why I think the film will be a Best Picture candidate. It's entertaining, it has a good if not great score, and most of all, it's a story that cuts across many demographics and provokes discussion. And films with good stories that provoke discussion generally fare well.
CZJ at opening night party for A Little Night Music, Dec 13, 2009.