I can't see it being Angela. She wants nothing to do with Asgardia after the revelation she learned in The Tenth Realm. And for them to color her hair differently now would seem pointless and idiotic. It's been said it's someone close to Thor, someone we/he knows. Thor is only "close" to Angela now because of blood, but that's it. And he only just met her, so he doesn't really "know" her.
Even though from what's been going on in Fantastic Four, I very much doubt it's Susan Richards. She's not even aware of what's going on with Thor. Plus, she just saw him in the last issue, so that takes place before the moment in Original Sin where Thor becomes unworthy. She's more concerned with her family than worrying about that Asgardia "must always have a Thor."
I was thinking, before the issue, that it could've been Valkyrie. And even though it seems obvious from the first issue so far, it makes sense if it's Freyja. She's no longer in rule of Asgardia, so this will be her way of doing something, for the lack of a better way to phrase it, than just sitting quietly as Odin rules once more.