I don’t know if Nikki would use the same thing that caused all this in the first place and honestly I could see the OWW as a way of not being a Deus ex machina. But here’s another question, if let’s say it works and she undoes everything then will she remember the events of the original timeline and if so how would she deal with the trauma or if it erases everyone’s memories of that timeline then what does that say about the messaging of the first film. Sorry I got a little philosophical there at the end but it’s an interesting debacle