I think Cheetah's redemption would hurt the iconography more than it'd hurt the in-continuity narrative.
Diana doesn't have a major, super well known villain like the Joker or Lex, but Cheetah is still Diana's most well known foe. Take her off the board and you limit an already under-developed rogues gallery.
I'm not saying it can't be done, and Cheetah has rarely added much to the larger story, but I think we'd be better off building her up as a villain. There's other bad guys who can be saved and redeemed, Cheetah's too close to iconic to waste like that.