so here sasuke says he is going to meet the one who knows everything
to me this i thought at first was madara - but know im thinking it could be the juubi, i will try to explain it best i can with as little words as i can.
now once Sasuke brought Oro back it went from the one who knows everything to them.
my thought is that sasuke can somehow find his way into the Juubi with his eyes and talk to the Bijuus abit like the same way he got into naruto and surpressed Kurama
what im thinking is with sasukes EMS he can go into the same place naruto went and talked to the other bijuus (first link) and talk to them thus giving him the answers he seaks and the juubi somehow will get feelings and thoughts (second link - dont view unless u want have seen thet new manga chapter 610 which is out on mangapanda)