Okay. As you all know, as of August 29th, Tobi has been confirmed as Obito. Right now, probably thousands of people are raging, killing themselves, or etc. Because they have devoted more than FIVE YEARS of research and thought of who the man behind the mask could be! They came up with several theories, and complex plots that they thought would be possible and said, "If Kishimoto really makes him OBITO... I'm killing myself, and he will be claimed the WORST AUTHOR EVER!!!
Wrong. You were wrong. Think about it. Word of wisdom coming your way. A writer never writes something in the plot (underneath the same name of the original) if it has nothing to do with the story. I'm saying that the Kakashi Chronicles were not in vain, of course. He put that story in BEFORE "shippuden" was introduced in the manga. If it were to be a side story just to explain WHY Kakashi had a sharingan, it wouldn't be in the manga, it would have been just an anime special.
So, why was it featured in the manga? Your answer, its just plain common sense hahaha, Obito. He was preparing you for the most logical and simplistic answer to this mystery he built. Fact: Almost every naruto character plays a part with the progression of the story. I could list anyone who has a part in the story who has either built another characters character and perspective and changed them in any type of way. Happens in Naruto all the time. Basically, the Kakashi Chronicals had two main keys. How kakashi got his sharingan, and why Obito would be tobi. Chapter 599, through out the whole thing, we see Obito living a hard life. He wanted to become Hokage, and he wanted to have Rin by his side! But, he was always considered a dead beat ninja. Just. Like. Naruto. He was always in the shadow of someone else, and he lost everything. He even didnt get to celebrate the success of passing the chuunin exams the way he wanted to. He was so alone.
In the end, you can understand why Obito would turn into "Tobi". Remember what he said in a previous chapter? "I am nobody." Pretty sad now that we know why, right?
Obito was the crybaby ninja, and she still is living up to his reputation. Lets think about some reasons why he would be living in regret. He didnt tell Rin he loved her.. He wanted to be with everyone for a long time? The way he was treated in Konoha? like poop? Yup.
Maybe he awakened his mangekyou before he was killed! Maybe Zetsu replaced the other half of his body that was crushed! So many things are possible! Also, people, we dont know the age of the masked when he attacked konoha and fought the 4th -.-. You cant just confirm he was an adult because of his voice -.-. Kakashi has the same adult voice when he was a teen, so it may be possible Obito had his too!
Basically, Just accept that Obito is Tobi. Theres no one else who could suit the role better than anyone else. I'm sure Kishimoto will make it all clear through the next few chapters. Just shut up and stop running around frantically. There is so much sense to come from this.