Rins death = Ms? maybe not...
The moment of Rins death we see that both Obito and Kakashi have 2 tomoe sharingan and not the 3rd.
Surely this means that ms is impossible from this event?
So what can we assume from this info? We can predict that obito received his ms between rin's death and the fight with the 4th only if we assume that his kamui powers are used with ms and not 3 tomoe shrngn.
So lets say that in 605 both kakashi and obito receive 3rd tomoe which is almost a certainty since their eyes are linked and they both care about Rin. (kakashi was crying) The next step of their eye evolution needs to be considered. Lets ignore kakashi for now and just focus on Obito. The only people who Obito can possibly grow to care about are Madara and Zetsu. Since zetsu hasn't died yet we can rule out his death as the cause of MS (less its faked or each clone has its own personality and spiral zetsu bites the dust. (which leads to tobi wearing the spiral mask as a sign of respect later)) We can guess that maybe Madara is killed by obito? A father-son relationship may develop over a years time since obito would have no one else to bond with. Then Madara may reveal moons eye plan to obito entrusting him with it then tell him that he cannot enjoy the life he's living in the condition he's in and asks him to remove the cords in his back. Obito does so, effectively killing his own 'father' and MS appears.
A few weeks/months later obito confronts minato where minato says 'Madara? no it couldn't be, Madara is long dead'
to which Obito replies 'I don't know about that' Because he knows that Madara only died recently. (rather than 'no he's still alive' that supposedly everyone would have got from it)
This is all based off the possibility that Rin's death doesn't lead to Ms or that Ms is not needed for kamui. Otherwise ignore this whole thread if 605 disproves this instantly
So yeah, what do you think?