Technically, Rijir is right: digital will never 100% reproduce film. He's not a stubborn ass, he's right--because film is actually organic and chemical based, there are parts of it that digital can only emulate but never totally reproduce. Things like random chemical fluctuations and unpredicatable reactions of light and such that is literally impossible for anyone to totally re-create; digital will eventually give us something that is about 95% identical, and for just about everyone including professionals this is visually indistinguishable, but there will always be that illusive, undefinable quality about actual real chemical-based film.
Its the same thing with digital paint. Give a digital artists a tablet, photoshop and some compositing software and he can make you a really good digital painting with digital paint simulators--but even as digital paint technology improves and becomes nearly indistinguishable from physical brushstrokes, there will still be a quality that a real hand-painted painting will give you that we will never be able to totally simulate.
This is why Speilberg says he will never work in HD--plus the pyschological and physical associations with working with film. It may also be that he will never work with the HD available in his lifetime. And i agree with him. Janusz Kaminski will never be able to photograph his films the way he does without using film.