According to Comicbookmovie.com when Jaimie Alexander, who plays Lady Sif in the Thor franchise, was interviewed by L.A Times’ Hero Complex, she spoke of her return in Thor: Ragnarok. Not only that but she also noted that there would be some teasers in 2016’s Phase Three films.
Thor: Ragnarok is to be the third instalment of the Thor story, with Thor and Thor: The Dark world as its predecessors. Jamie Alexander has appeared in both Thor films and even Agents of SHIELD. Her story and place in Ragnarok is definitely not known and the interview did note that “[Jaimie] will be in Thor 3 and will be a very pivotal part of the Movie.”
She did give one note for the fans were to keep an eye out for things when Captain America: Civil War hits as she will cameo and: “There’s just all kind of Easter eggs and hints, if you’re really paying attention. They’re so good at interweaving everything throughout those films.”
We know of the famous post-credit and pre-credit scenes of many of the Marvel films but the entire cinematic universe, including the TV series’, are filled with little hints and Easter eggs here and there.
According to IMDb Thor Ragnarok is set for release in October 2017 in UK and November 2017 in US although these dates may change.1