Its possible , because i don't see a creature that is the source of everything and progenitor of the world as a mindless destroyer , but its possible also that someone controled the juubi against rikudou senin and that explains the rampage and evil or someone erased juubi mind to make it as a feral bijuu and manipulate that bijuu as an weapon in wars... i don't know if juubi will get a mind but there is chance , or madara will become juubi jinchuriki as the last main villain
"When I watch this boy, I think back to when I was once called a genius, and realize how ridiculous that was." - Orochimaru
Re: The Ending Of The Series
First off I want to say that, as usual, your theories are a thing of beauty.
But the thing I have against it is what gives kurama credibility? I mean the guy only came into existence prior to the juubi's sealing and so he has no 1st person knowledge of who or what the juubi is. The closest thing he has to knowing what the juubi was like is if the SO6P's told him what he was like. And even that is a little shaky as we dont know the sages motives which kinda ties back into that theory I made a while back about the sage being a bad guy.