It almost feels like he has already been forgotten. I know shit got real, REALLY QUICKLY! But no one has said a thing about Yamato since Naruto first found out he was taken. I would have thought Naruto would have asked Tobi about Yamato... I know Kabuto took him but Naruto and the gang know they were working together at least a little bit. Good chance Tobi knows something about Yamatos fate. I don't think he would be willing to share to many details about it though.
I know whats going to happen... right after Naruto defeats Madara and Obito... AND SASUKE! Yamato is going to appear wearing a white robe, and wielding a sword for some reason. He will than extend his sword and say Kyōka Suigetsu Shatter... Out of no were a splash of blood sprays out of Narutos chest, then the series will end. But the very last panel will have him saying... "What... You thought I could only be in one series!"