ually, I think Sakura's reaction depends on the direction of the rod. There are three possibilities (for the direction of the rod):
#1. At Sakura
#2. At the kunai
#3. At Obito
No. 1 is very likely as Madara says "I won't let you".
No. 2 is not that likely as I don't think Madara has any use for Sakura to spare her. Killing anything of no use to him is more his style, I think.
No. 3 is very unlikely as, like I said before, Madara says "I won't let you".
But it all depends on Kishi. And his plot.
Now if No. 1 is to happen, these are the possible reactions i've thought of:
= Sakura dodges it
= Sakura blocks it using her kunai (unlikely, but still)
= Sakura gets hit (and dies or heals herself)
= Obito tries to protect her by taking the blow
= Obito uses kamui on either Sakura or the rod
= Obito pushes Sakura away
= Obito uses his staff to block it
If No. 2 were to happen:
= Well, not much may happen, but either a dialogue/conversation takes place or Madara goes straight into battle mode.
If No. 3 were to happen:
= Sakura blocks it using the kunai (again, unlikely)
= Sakura protects Obito by taking the hit
= Sakura pushes Obito away
= Obito uses kamui on the rod
= Obito gets hit, may be critically injured but won't die, yet
= Obito dodges (unlikely, given his current state)
= Obito uses his staff to block it
Well, I endured a lot of back pain, but I think it's worth it!

These are the 'scenarios' I've thought of. What do you think???