I think it's really REALLY difficult to say. I mean, certainly I can tell you movies I really like, but as far as what survives in 50 years? I don't know that people will still consume entertainment and movies in particular in the same way 50 years from now. New stuff is released at such a breakneck pace anymore that it's tough for it to really stand out. I suppose that was true in the past, to some degree, but I really think it's difficult to guess at what will still be watched 50 years from now.
Plus, think about all the old movies today....that kids totally ignore. There's a reason why you see all these reboots of films from 20 years ago -- it's because nobody's watching the old versions anymore as kids. So, really, will ANYTHING be watched 50 years from now that's being made today? I'm honestly not so sure.
I think there's also a big difference between "what will be regarded as an artistic masterpiece 50 years from now" (e.g., studied in film school and such), and what will families be watching as "Oh, I loved this movie. I'm gonna make my kids watch it."
I could see where, for example, Brick would be studied in film school as a further development of the film noir genre. But I doubt it'll be a well known classic years from now. Likewise, I could see where, say, Ghostbusters or A Christmas Story would still be watched, not because they're so artistically amazing as films, but because they're "classics" that people grew up with and will want to share with their kids, thus their status as classic films will be transmitted the same way as, say, The Wizard of Oz.