Oh gosh that last part. I've thought about that too. But who would she save him from? No one is to confront him except Naruto, and I could see her doing it for Naruto more.

When you put it that way it makes sense that the person Sakura has to protect is Naruto.
Besides, we already got that panel in the Summit arc in which Sakura decided she wouldn't be involved anymore in the conflict between Naruto and Sasuke.
I could see it this way:
- Obito is about to stab Naruto, but Sakura gets in the middle and gets stabbed in his stead. ( I think it would be different from Neji since the one he protected was actually Hinata, although Naruto made it more about him

)
- As Obito sees himself stabbing Sakura he flashbacks to that vision he got of Kakashi killing Rin. I think the point of making Obito first see Rin being stabbed through Kakashi's POV is so that he can remember that exact image when he does it to Sakura.
- Naruto gets emotional, maybe something happens between him and Sakura as she dies
- Obito realizes the parallel between him and Rin compared to Naruto and Sakura
- Naruto keeps moving forward to defeat Obito who's resolve starts to waver seeing as how Naruto did not take the same path as he did. Also, Obito realizes that he has become the same darkness that led Rin to die.
- Eventually Obito has his change of heart and Sakura is brought back to life
Many things would happen in between, but those are the point I wanted to bring up in relation to Naruto and Sakura.
I know some people don't want Obito to be redeemed, but I think as of now it's building up to it. Besides, we still don't know why Kakashi had to kill Rin, so I'm assuming that's being saved for a later date because it will prove significant for Obito's character development.