Re: Christopher Eccleston is playing Malekith
Malekith being the main villain doesn't exclude Amora and Skruge just as Loki being the main villain didn't exclude Laufey or The Destroyer in the first movie.
Natasha Romanoff - "Are you boys really that naive? S.H.I.E.L.D. monitors potential threats."
Bruce Banner - "Captain America is on threat watch?"
Natasha Romanoff - "We all are."