On the other hand, if I may get conspiratorial, maybe Valkyrie is undercover as part of an Asgardian sting operation where the endgame is dismantling Grandmaster’s cruel games!
Regardless, it stands to reason that eventually Thor and Valkyrie will team up in some capacity during Thor: Ragnarok.
That said, the fact that Valkyrie is working with Grandmaster suggests that she’s left behind her Asgardian life.
There’s still a lot of mystery surrounding how Valkyrie will specifically be involved in Thor: Ragnarok, but as with every good superhero character adaptation, elements from her comic book past are being kept intact.