Yeah I also noticed the similarities between Misty and Tempest Shadow, which means Opaline’s promise to give Misty her cutie mark is a lie and she’ll try to kill Misty. Then Misty will be saved by Sunny Starscout and she’ll reform.
Of course if this plays out Prune Alicorn will be betrayed and killed by the minion that she strung along and used. Because the one thing we learned from the CMCs is that no one can give you a cutie mark.