Obito woould have Not, been Killed,Obito would've been "":flaw:LiTerrallY:flaw: RAPED BY ITACHI in the most horrible and painful way..If Obito was never crushed by the boulder, wouldn't he by then be a victim of the massacre and still be killed later on? Or would he have been strong enough to stop Itachi, I mean what age would he of been when that massacre occured?
And general what role would he be playing if here were alive.