At this point I'm almost certain that a karma seal will find Shin Uchiha. His body will not reject it and he's just wandering around somewhere waiting to get revenge on Sasuke. Once Jigen and Kawaki are defeated Shin will be the madman trying to take the power of the chakra tree as his own. He already had a mini Juubi that he used for teleportation. How did he get that? There are still dangerous enemies out there other than Kara and I wouldn't be surprised if the Akatsuki made a comeback.