I can't see this ruining Fury Road, but I think the concern would be that, as we already know she's alive and with a mechanical arm by Fury Road, alongside Immortan Joe (who is also in this prequel), there's absolutely no "threat" to her (or Joe) at all in this film, as there is literally no way she can die or be permanently hurt in any other way than we've already seen, which just leaves "how" certain events happen rather than "woah I didn't see that coming" etc.
I mean if 2 of the the main characters are effectively immune to death, if there's no potential risk in their story etc to me that makes them less interesting from a story telling point I think. I would suggest that it also probably means the "risk" in the story will have to be held around the only other main character, Hemsworth's "Dementus" as minor/side characters aren't all that important, which again narrows down creative choices.