Let's see. Some facts. Though not all are.
1) She feels she was fucked with because Kyubei didn't tell them the info bit about the SG (because they never asked... duh)
- Kyubei emphasizes on the body's utter
advantage when seperated from the soul, the painful way
2) She turns emo, deep in thought so she doesn't go to school
3) Then she meets up with Kyouko, this has more importance on behalf of Kyouko
4) Sayaka's ideals are strengthened as Kyouko is the example she doesn't want to follow even if they both started with the same mistake as Kyouko stated
5) ^might have pushed her to be able to go to school again, or she recovered without influence, doesn't matter
6) Confrontation with Hitomi... dun dunn dunnn we all know what happened
- Sayaka feels regret for the first time, contradicting herself
- What's left is sadness and irritation ---> Lowest self-esteem ever, gave up on Kamijou
(probably)
7) Ahh the light! It's so... pink!! Oh wait, it's just Madoka. Yosh yosh, it's all right. Let's go some witch hunting
8) Sayaka made up her mind (lol yeah sure) and there's only one thing she can now be optimistic about
: the
advantage
Which leads back to Kyubei. Good job Kyubei, you helped her realize that she isn't worthless as a zombie! Come on, she is even so happy she laughs out her ass when she literally feels that her body can take more than... well, a non-MG body. (half joking)
Spoiler for speculation for Sayaka:
She is kinda going crazy but I believe while she will approach things much more radically now, at this point she is still... well, Sayaka. I mean, Kamijou also had a OMGWTF moment and he ended up just fine the next episode.
I can understand that she would be willing to not save Hitomi anymore in case she is influenced by another witch, but getting manipulated twice seems unlikely (not impossible). What I can't imagine is that she will kill Hitomi (as Sayaka rather ignores the problem than approach it directly), so that leaves me to think that Hitomi will have a chance to live through shit.
Not sure about Kamijou though. My take is that he will reject Hitomi. He will realize that his feelings prefer Sayaka. Maybe Hitomi, after being rejected, also at least wants to support the Kamijou+Sayaka couple as she indirectly did before. Even better yet, he will be able to make Sayaka understand who already gave up on him! But... in vain. I imagine he will somehow be caught up in dangerous events that might have him killed. In case Hitomi is also with him (a la let's tell Sayaka together), then both get caught up. And die.
"I'm so stupid" (next tag line)... -> because Sayaka noticed things (such as actually being not too different from humans just with some advantages and disadvantages you can avoid -> Aikawa Ayumu style) too late / gave up on things too early which will finally lead to broken Sayaka.
Alternative: Hitomi will die, Kamijou will live. Sayaka didn't lose what she found to be important, but she will lose someone that >is< important to her which gives Sayaka's victory more than just a grain of salt. She still won't be happy.