Hey guys so as you know spirits are a big thing in Naruto and even after a Character dies, there spirit may lie somewhere else.
Such as Kakashi and his father
And Gaara's mothers will in Gaara, having that form of spirit too.
Maybe you could even consider Minato and Kushina as well since they still lived somehow even though they are dead.
Rin too could have the same affect, she always states she is looking after Obito
In this scene I want to stress the fact that Obito had a LOT of flashbacks while training in rehabilitation (thats what kept him going) and the ONLY flashback to have verbal communication is that scene.
Maybe somehow she is still out there in a form we have yet to see.
Rins is there to balance Obito and Kakashi's situation I think
Maybe kakashi and Obito will have a high rank shinobi moment trading blows where Rin will make an apperance
IDK just thoughts based on Manga