Board Thread:Naruto Discussions/@comment-24531362-20140904111518/@comment-24593592-20140909130009

Elveonora wrote: No, Hagoromo knows Obito died, he just thought that he had already gone to the pure land, that's why he said he would ask Obito by himself once he comes back, but then Hagoromo realized that Obito is still inside of Kakashi

Depends on the translation. MS mentions nothing about him saying "getting back". And it doesn't make much sense because Hagoromo never went to the Pure Land. He lived on as chakra watching his children fight for ages.