Easy question.
After the convo with the former Hokage, Sasuke's going to go like:
Sasuke: **** this, let's level Konoha, and I'm definitely gonna kill Naruto.
Suigetsu/Juugo: When?
Sasuke: Right now, it's been a long time coming.
*decisively heads towards the exit, ready for destruction...Karin shows up!*
Karin: Finally I found you Sasuke!!!!
Sasuke: how the hell are you even here? Doesn't anyone stay dead anymore? God dammit.
Karin: There's something very important I wanna tell you!
Sasuke: Oh shut your mouth, I'm about to achieve the revenge of my life as soon as I step out of this door and you come around and...
Karin: I'm pregnant.
Sasuke: ...
Sasuke: FFFFFFFFFUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!