Yes, she will Jaimie Alexander confirmed it herself, and on the poster it says her name.

You're in luck!

These rumours went around a bit while back, and I'm glad we got something out of them in the end. Not sure what kind of role she'll be playing, though.

Yes

I believe it was confirmed by Jaimie Alexander and some others that it was confirmed that Lady Sif would appear in the sequel

I always assumed thanos killef sif when he killed half of the asgardians

I think Sif was on Earth during that.

Ahh okay. Thanks guys!! So excited for the movie!!!!!!