After all we've learned, it seems pretty likely to me that Sakura will have Sage Mode.
I mean, think about it. Byakugou is possible, but Tsunade said that she was the only one who knew how to use it. It's possible that Sakura learned it without Tsunade knowing, but I don't think so. Besides, Tsunade is the one who created the jutsu, so Sakura would probably have to go to her to learn how it works, right? She's smart, but she would still need her master's help, I think. Plus it's a forbidden jutsu. (Though, granted, that's never stopped anyone before...)
And the Japanese text specifically and conspicuously left out what Sakura was gathering. If she was just storing chakra, then why would they leave the word "chakra" out? Most people would think that she was just gathering chakra to be able to fight at her "full power," not exhausted (do you get what I mean?). Or, even, the Yin Seal/Byakugo.
But if it had said natural energy, of course everyone would guess right away what she was about to use, and Kishi doesn't want that. He wants it to be a surprise.
And if she was storing chakra, wouldn't she need somewhere to seal it? Like the diamond on Tsunade's forehead? I dunno.
Plus, with her having Sage Mode, she will have surpassed her master, like Naruto & Sasuke have. Especially since the Creation Rebirth/Byakugou shortens the lifespan of the user (which would not be a problem in Sage Mode).
Sage Mode will increase her abilities, so she'll be even more useful during the fight. Byakugou would only heal her injuries, and while that's certainly helpful, Sakura will have to be strong in order to do some damage to the Juubi, much stronger than she is now. And she said she would be able to compete with Naruto and Sasuke, and I just don't think Byakugou would be enough to make her say that, since it's just a regenerative jutsu.
However, I also think Slug Sage Mode may have regenerative capabilities as well, given that slugs can regenerate and all.
Maybe there will be some sort of clone jutsu associated with slug sage mode, since slugs can automatically amputate parts of their body to escape an attack and they can regenerate portions of their body, so combine those two... And Katsuyu also has this. It's unlikely, but it'd be cool.
Of course, there's the problem of when Sakura learned this. After she learned about Sage Mode, though, maybe she could have started looking into it and all that. Often after she hears about something she'll start researching it. So after she heard about Sage Mode, she would learn about a slug sage mode and decide to master it, some time before the war arc. That may not seem like enough time, but remember, she's sharp and a quick learner and she would know how useful it would be during the fight, so her determination could have helped her learn sage mode even faster.
I don't see the point of mentioning the Shikkotsurin if we weren't going to see Slug Sage Mode. Well, Hashirama's is probably slug sage mode, but Kishi didn't focus on it, so this would be a good opportunity for us to learn about slug sage mode and what, specifically, it can do, while also giving Sakura a huge power-up.
About Hashi's Sage Mode... He has a technique Sage Mode, not an animal Sage Mode.
If you have noticed, all the Sage Modes till now, except Hashi's, had the animal name Sage. While Hashi's the technique, aka Mokuton.
So that's why I am certain it will be SSM on Sakura.
From the big 3 animals, Toads [Frog Kata] and Snakes [can't remember the name cause I didn't research too much on it] have the name of the animal summon, whereas Hashirama once again, I say, he had it's Mokuton.
And if you wonder about why he has regenerative abilities, think about it. Hashi creates life forms from the Mokuton, so it's only normal to have some regenerative abilities as well, given his technique.
But from the Big 3 animals, one is missing, and Sakura is hinting at something. Shikkotsurin wasn't mentioned in Hashi's SM.
Well, guess what remains?
