Re: Will the Casket of Ancient Winters be in the film?
I do appreciate attention to continuity, and would prefer that the casket not simply be forgotten about... but more importantly, it seems as though the Aether is one of the Infinity "stones".
Odin mentioned that other powerful relics were usually stones, in the opening monologue. Then Volstag and Sif brought the Aether contained in that little box, to the collector saying that since the teaseract is already in the vault, it is not a good idea to keep 2 infinity stones together.
So they blew right past the casket and went to infinity gem/stone number 2.