During a live facebook Q&A in support of her tv series, Blindspot, actress Jaimie Alexander was asked a question she confessed she gets a lot.
"Am I in Thor 3? I get asked that everytime I do this!" She said, about seven minutes into her chat with fans. "I actually don't know. I have no idea," she admitted. "I'm guessing no? But I'm not sure, because nobody's told me. I have no clue."
So, Lady Sif apparently hasn't been contacted about joining the fight in Thor: Ragnarok. It's a bit of a surprise, after Alexander was a critical hit and fan-favorite in the first Thor, and played the role of the Asgardian warrior in both Thor: The Dark World and Marvel's Agents of S.H.I.E.L.D. on ABC.
happy hump day! #24Live BlindspotPosted by Jaimie Alexander on Wednesday, April 6, 2016
Thor: Ragnarok is in pre-production, having started in January, with a set start date of June 2016. The movie will film in Queensland, Australia, the native country of star Chris Hemsworth, Marvel Studios announced last October. The timing is right if they want to call Alexander in, as she'll be on summer hiatus for her NBC series, but apparently that's a call she hasn't received yet.
The plot of the film has been kept largely under wraps, though the Hulk (played again by Mark Ruffalo) is confirmed for the film, as is Loki (Tom Hiddleston). The title implies a connection to a Norse Mythology event wherein the gods go through a cycle of death and rebirth, something that would surely need to include Asgard (and popular/known Asgardians like Lady Sif) in the story.
Thor: Raganarok is set for a November 3, 2017 release date. Blindspot airs Mondays at 10pm on NBC.