The social network is of it's time and will date really badly, to the point where no one will watch or mention it ever again.
True Grit is a remake so specifically cannot be included as it had to be good enough to have been remade.
Inception isn't ever going to be a classic a la The Matrix.
The Kings Speech will definitely have longevity; Black Swan I'm not convinced will float above just being another film you can pick up for £3 in HMV in a couple of months but then think "well, will I ever watch it?"