1. What the hell is Naruto thinking? The shins were about to go after them despite their "father" being weak, multiplying wildly, Sarada goes after them to protect her mother, punching the guts out of them, and Narutos just like "*We aren't being very nice you guys. Lets take them home with us."*
2. YES! We finally know that Sakura is the biological mother. While I am ecstatic about that, though, Sasuke just leaves again, and despite things calmed down and not having seen his wife in God knows how long, doesn't embrace her in any way. Disappointing behavior on Sasukes part.
3. Kabuto, the man who infused a diabolical snake man's body inside his own... We're talking about the same man who revived dead bodies of the most powerful shinobi and turned them against the shinobi alliance... Is in charge of raising children?!? Uhh.. It's sweet that he changed his ways, but I mean, who let him be the main influence in little kids lives...?
I think the mother is Sakura. (I also HATE that they updated the wiki saying Karin is the mother without any proof.)
1. In the latest chapter, we see Sarada has Sakura's temper and her moves. You might say her moves are taught, but you need excellent chakra control like Sakura has to punch like that. And, we saw that Sakura was born with good chakra control in the original Naruto.
2. I don't think Kishimoto would make everyone think Sakura is the mother, then decide its Karin. That's a crappy thing to do, not to mention a terrible dick move on Sasuke's part in doing Karin, then returning and marrying Sakura dumping the baby on her and leaving.
Now, MAYBE if Sarada is a test-tube baby and has Karin's genetics, I'd believe that.
A person theory I have, which might be far-fetched is that Karin is working with the Shins. She wanted a child to have a vessel for Shin, so she used Sasuke's DNA and mixed it with her own to create Sarada. For some reason, Sarada was taken away from Karin, maybe due to suspicions of her intentions. Then, Sasuke as the biological father took her in, or Sakura saw her, working at the hospital, and took her home.