^_^;
I feel so alone again. Amazing to which different results people can come.
To repeat my prediction:
o Sayaka will be screwed over and dumped by Kamijo
o Feeling crushed and betrayed, Sayaka will refuse to do her MG duties and turn into a witch
o Witch-Sayaka will be killed by Kyoko.
So. If things come to pass like that (I give it 66% probability), then Kyoko has done nothing wrong for which she should be attacked by Madoka or Homura. She's not responsible for Sayaka's fall, and as a MG, it's her duty to kill witches.
(IMHO, this is the function of Kyoko on the Meta-Level: A Sayaka-turned-Witch has to be killed, but not by the hands of Madoka or Homura. Therefore, we need one more MG character to do it)
And I see no point whatsoever in making her a "Mid-Boss" or anything. For what? Revenge? Is that supposed to be what this show is about? Most definitely not. Therefore, I also see no point in having Madoka/Homura trying to kill her or something.
No - I'd rather expect her to become a rogue resource. Long-range prediction: Madoka will try to get along with her, but Kyoko will ridicule Madoka's idealistic-naive ideas. However, somehow at the very end, after a long struggle of Madoka's to convince/befriend Kyoko, she will be instrumental in helping out Madoka/Homura in a critical moment. Entirely against her own selfish convictions. And by doing so, lose her life. So, if she dies, it will be in defense of Madoka/Homura, because Madoka managed to convince her to ignore her selfish ideals for once.
That's how I expect Urobuchi to deal with it, at least