So I guess I'll throw my theory in for an event coming up in manga.
Its the Obito to Sakura request, yes, how can this be NS? Well many are suspecting that in someway, maybe again there could be some relation or memory Obito makes of Rin.
Otherwise the current battle with Naruto and Sasuke facing Madara. A real unique situation has arisen, each Uchiha alive has a Rinnegan. Madara only has his right eye, Obito has madara's left, and Sasuke only awakened it in the left. So there are 2 even out theories I got from this.
At this point, its equally viable that Madara will get or not get his other eye.
The deal with the first one though is just how will madara get it?
Two ideas came to mind for this, and this is assuming obitos request involves the rinnegan's containment or destruction:
If Madara gets his left rinnegan back:
He simply takes it back from Obito or by Black Zetsu (provided black zetsu wasn't impacted by the removal of Yin kurama or manages to take advantage of obito again). This would have to occur in some way with obito coming back from the kamuai dimension or something else happening along the request.
If he doesn't get his left eye back:
1. He improvises and takes Sasukes, kinda going on what he said when he was blind. Sasuke has a left eye, taking that will cause a bunch of chaos.
2. Best case scenario for the heroes, the rinnegan is destroyed and instead he comes to rely on the tree for his power.
This deal of Sasuke having a left Rinnegan and Obitos request to Sakura got me thinking and while it would entail some action from transplanting there were a few things I thought of that seemed more reasonable.
-Sasuke having one rinnegan is almost again, ideal for madara to just take. Obito's request would otherwise be involving the rinnegan, trying to deny an assest to the enemy. If anything obito could be anticpating black zetsu to resurge and mess with him, obviously on Obito's end, its possible for a Sakura-Rin parallel to occur, but the transplanting stuff could come by a different means. I don't expect Sakura to die, obviously she needs to live for an event like a transplant to occur. Though then it seems like we may get a similar power down power up moment again like when naruto lost and regained kurama. Though how would the transplant event occur if Sasuke loses his own rinnegan born of itachi's eyes?
Here is how I would expect the moment to go down:
I would expect Sakura to actually be hesitant at first, giving the great power she knows to one like Sasuke who she currently distrusts, it would be such power she may be heistent at first because she knows that Sasuke has other motives but because of the situation and otherwise naruto's instruction, she would do it anyways. In one part for the team, but in another she would have a reason to be worried after doing it for what comes after the fight.
Though its evenly viable for either madara never getting a left rinnegan or a transplant event to occur. Obito's request can be simply destroy the rinnegan or keep it safe. Otherwise it could be unrelated to it. I mean in all matter of events like this, there are a few things to make out:
-Sakura isn't going to die, she is a main character. even if she becomes the high priority target holding the rinnegan or her role is something else like fighting black zetsu or simply destroying it, she has plot armor because she is important in the end, not in the current stuff involving the sage but in the stuff when it comes to team 7. Literally even though some fans still want it, killing sakura does no justice to the story nor help NH as many other fans want. It wouldn't change the fact that kishi still didn't develop NH as he could have and would otherwise reduce hinata to a full fledged fodder token pairing character. The most convinent of all simply because sakura was axed off.
- Its both possible that Madara could regain his rinnegan, steal sasuke's or never get his back. Again all are viable.
-A Sakura rin parallel could come (at last) despite other events, part of the event having just obito and sakura could otherwise be memory inducing on Obito simply because, well how freaking relatable does kishi need to make rin like sakura?
Aside from sakura being a main character, she more or less is going to live in the series. A Sakura-rin event is possible as well. The other stuff, it all depends on what obito's request is exactly and what madara does in the battle. If Madara uses the tree more, he may not care about his left eye anymore. We just need to see how both events go.
On a side note, Its looking like Naruto and Sasuke are not healing hands people so least Sakura is still the medic of the group. While they can manipulate another's chakra they cannot heal them, so ceasing the effects of a jutsu like opening all 8 inner gates is one thing, healing would have to be another. I really believe that after this obito request sakura will simply be the one to heal guy,
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. Its an interesting assumption and i agree with it 
