You are completely wrong or at least you made some huge misconception on exactly WHAT oro wants. Read my above post for startes.. Anyway the sharingan allows the user to easily copy jutsu and learn it really fast. Tajutsu is easy, sasuke has done it with Lee for instance. Kakashi is called the copy ninja because he has 3 chakra affinities, and thus he can copy a ton of jutsu.
Rinnengan DOESN NOT let the user copy jutsu.. Surely it gives you 7 unique abilities, but that is way too little compared to what oro dreamed for....... And as I said above, the rinnengan hadn't even been introduced yet. It was introduced along with Pain right before the time skip I think. No way Kishi wanted to give a hint here xD it's not like he thinks it that much through. The group of people he is making the story to is school kids. No way they gonna go back and find something like this even after the rinnengan was made....
Of course Rinnegan doesn't let you copy jutsus, what it does is allow to learn every jutsu that the world has to offer, based on the 5 elements. Like I've said multiple times, this excludes things like KG and KT, but it is a sort-of upgrade to the copy ability because it is allowing you access to more new jutsu than the sharingan did. The only fact I was concentrating on was that Oro was talking about every jutsu and its hard to argue he's talking about the sharingan because of that simple fact.
Nice find, while I do believe Kishi has had everything planned out from the start, other translations and the Anime translations disagree with you.
Here is one for example.
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Most translations I've found Oro is "Defining a Ninja" or Talking about his ambition. Not the rinnegan, or the sharingan in particular. I would encourage you to look into other translations and watch the anime episode again. Might help you piece together your theory.
You are right about the anime, typically their translations are 100% accurate, but manga is a different story. If you find one group of translators that translates one section right, they likely translated anther section wrong. What I'm saying is I have yet to find one translation that seems to get everything right. By chance, what website did you find this from? Of all the translations I looked at, none of them matched the one you posted.
More on the topic, finally someone tried to discount my theory without straight up posting, "Nope, he was talking about the sharingan, you're wrong." None of these people had any proof to counter my claim because simply none existed. We all knew Oro's final plan included mastering all jutsu and we knew that he hypothesized that sharingan could become rinnegan, so it was possible. You are the first to actually present a valid argument against my theory, and I commend you for it.
Now its still possible that either translation is correct, but I feel that yours is more accurate. With that being said, I cannot really state that this is a direct reference to the Rinnegan, I think that much is clear. But Oro is still talking about a person's ability to master all jutsu. We always knew that Oro's goal was to master all jutsu, but clearly no normal person can do this because no one has access to all 5 nature types.
So in a way, this is still referencing the Rinnegan, but its a much more subtle reference when comparing this translation to the other. Again, we always knew it was Oro's goal to master all jutsu, so with the knowledge we have now, its clear the Rinnegan was within his plans for the future. Either way, I love that someone actually put up a valid argument against my post, but I still think the reference is there, just not as clear as the translation I was basing all this off of.