We don't even know if what Suigetsu tested was a cord. Unless I was reading too fast, I didn't see any mention of it being such and it didn't look like one to me.
Yes there is still a 50/50 chance, even after this because:
1) Suigetsu was unsure if this was even the correct sample
2) Naruto appears to not even know.. which is weird because he would had to have seen Sakura at some point. I don't remember her leaving for a year. Then again I didn't see The Last, so I have no idea if it was stated there or whatever.
3) Why would Karin keep a sample of her own DNA in her own desk (flashback implies that was her desk before she moved bases)? She has a source of her DNA 24/7 with her own body. For all we know that could be Sasuke's DNA she has kept.
4) Sasuke expressed his love to Sakura (in his own way) at the end of 699-700(?). Why would Sasuke willingly hurt Sakura by having a baby with Karin instead of her? Especially if they were together and also getting/just married. He called her his wife as well in this manga. Actually, they have both harped on "husband" and "wife" in the last two chapters. On top of this Sakura has been wearing the Uchiha crest, which I'm sure he wouldn't like if she wasn't part of the 'clan'. So this makes me question how messed up Sasuke still is if he would emotionally hurt Sakura (who he was and still is with/married to) and then make her take the kid in.
5) Karin seems like she'd be over protective of her child, especially if it was Sasuke's. Why would she give the child to Sakura?Orochimaru knows if he ever went after the kid, Sasuke would come at him with everything he has.. so she wouldn't be in real danger. Also, why would Sakura take the kid anyway? So she fits in with the others? She seems to care too much about Sarada considering she is supposedly the bastard child of Sasuke's.