As much as I hate to say it, a theory is a way to connect facts together and come to a conclusion, and attempt to prove that the theory can successfully connect these facts.
Your "theory" is not really a theory as much as pure speculation. For one, the sealing jutsu used by the 3rd when fighting Orochimaru he used to seal two previous hokages in addition to some of Orochimaru. All while being stabbed and very old. Just imagine if he was younger, stronger, and only had to seal one person.
The 4th sealed the Kyuubi into Naruto so that eventually the two will fuse together. This is why Naruto tends to have a huge amount of stamina, and the Kyuubi inside him has gained some human intelligence and isn't just a simple beast. The seal was brilliant, which is what makes Naruto potentially the strongest ninja despite him not being a genius.
Your idea of a "Rasengan" doujutsu is completely unfounded. You ignored the facts of the
manga of how theres only 3 eye techniques, that they say EXPLICITY which technique was used to seal the Kyuubi, and made up your own facts instead.
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