This theory is quite plausible. The only thing that throws me off is the source of Sharingan and Rinnegan. The reason I may disagree is simply due to origins of the Elder Son's eyes as well as the logic of Uzumaki's actually. Also, the Uchiha Tablet seems a little too far fetched with the Uzumaki's. But then again, you have even more evidence to make up for those points I disagree with.
My reason is the SO6P may have came from the Uzumaki clan or a special group of people with sealing techs. After sealing the Juubi, he marries a wife, and have his own family. In the process, the chakra and powers are slowly seeping into his sons, because you have to understand that SO6P could not full contain the Ten Tails chakra, because the Ten-Tails. So some of them leaked out. The powers both his sons had may have come from the Juubi, considering the Uchihas have a special type of chakra that creates Sharingan and the Senju having a incredible life force.
The Senju's life and physical force and the Uchiha's special chakra that Tobirama said that activates Sharingan may have actually been from the ten-tails, as you saw that Naruto inherited the whiskers before he became Kurama's jinchuuriki's.
Rep for effort.
You have about 10 times much more evidence and logical explanations than that other post the Sasuke will be the next SO6P. I laughed even harder that some actually agreed with him, especially if you read MinatoTheYellowFlash's post, you will find how absurd that post is like the thread itself. Nothing against them, but they are really Sasuke wankers for believing that type of crap.
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But again, very great thread. Don't be too sure about like that last thread about Shisui. alright?