Board Thread:Theories and Speculation/@comment-28819877-20170515143845/@comment-734582-20170515162228

LovelyFox wrote: Well, Sasuke got his eye instantly, just like Naruto received his own TSBs. Obito got his TSBs either but without Rinne anyway. So i doubt he would have awakened it later. As i mentioned before, Hagoromo was involved. The guy who summoned spirits from the afterlife, split the Ten Tails into nine unique beings, and got back from the afterlife for however long he liked.

Madara awoke his Rinnegan naturally and it took decades. Sasuke got it instantly from Hagoromo. If Obito were to awake his own, it would take decades as well. But he's not really a transmigrant. He'll never awake the Rinnegan on his own because his flesh/chakra won't change due to Hagoromo's presence. madara awakening the Rinnegan is similar to the Juubi being reborn, individual components recreating a power beyond their individual selves.