Board Thread:Theories and Speculation/@comment-3001903-20151205022433/@comment-734582-20151208141435

GreatestSin wrote: "cant handle them" is more linked to "will not be able to get them under control no matter what" because of stuff like the war and the plan needing execution, there wasn't any way he could have have enough time to master the eyes. thus, for all intents and purposes, there was no way he could control both eyes, no matter what. The option that he learned both eyes didn't exist, therefore it's the same as not being able to control them at all.

He also said he almost lost himself controlling just one eye, suggesting it's got to do with willpower, not physical power. Having enough time to learn them is no guarantee that eventually he can. Obito controlling both eyes is a possibility, but not a certainty.