Re: Thanos and Loki
Based on the demand for more Loki I could see him appearing at least in a limited role where he shows up in the beginning/middle and then again at the end
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."