Some spoiler if you havent read enough
Tbh, I dont believe this because it havent turned out like this in the manga. To start things off, if the 4th is the masked one then it must mean that he lied to Naruto when he explained to him about his fight with the masked man. Another thing to note is that according to the characters opinion in the manga, the 4th sealed half of the kyuubis chakra inside naruto at birth after having fought the masked man selfproclaimed as madara but we still dont know his real identity of him, the real madara knew the person. At that time, madara should still be dead due to not having been revived yet, which makes it nearly impossible for your idea about the 4th being the akatsukis leader, further more Naruto was supposed according to his wish to make use of the kyuubis chakra and become hokage, as one appreciated by the people around him, now if the 4th as you mentions there would be the leader of akatsuki would want it back just to make use of it himself then that would mean, Naruto would have to die. That Gaara managed to survive were only a one time occassion, Naruto would definitely be dead without any exception if the kyuubi would get taken from him.
Kabuto did never help Sasuke to kill Orochimaru, Orochimaru were already weakened due to the body couldnt handle it anymore, so Sasuke could easily handle Orochimaru with the help of sharingan, later on it came to that Orochimaru still had an ace, however Itachi were the one to give Orochimaru the final blow by sealing him into that national treasured sword which Itachi had. Yes Orochimaru still got his special techinque at other people but his remaining chakra is currently being sought up by Kabuto whos trying to become one with him, or at the very least with his remains.
In the end, what you have mentioned dont seem to be the true end but an alternative end which separates from the real one around the fight between Pain and Naruto. My belief is also that you got this alternative story from some fansite or fan community who couldnt manage to keep on following the original. If you want to sound more reliable then you better provide your real sources instead of directive of some unkown source X.