Wow man...! I have an MA in philosophy, and I never have nearly thought about something like that... But, yes, your theory points some pretty nice possible features of One Piece and its resemblances with a hegelian vision of history...
Let’s talk about Hegel. As you may know, Hegel is a modern thinker: and modern thinkers use to think that there is just one history, THE history of humankind, and that that history is the history of western civilization. Postmodern thinkers, and mainly postmodern societies have shown that believe to be false: there is no just one history but many histories. For instance, Japan never had something like a French revolution. So Japanese doesn’t know or live something like a popular movement searching for freedom or trying to liberate of a Monarchy, how it happens in many western nations.
This raises many interesting questions, which I can’t answer. What idea Japanese have about freedom? Is it that idea as important as it is for French people or as it is for western contemporary civilizations? I’m not enough familiar with Japanese culture to give an answer. But it is interesting to think about it. Japan has had monarchies; in fact, in present time, it is a Monarchy, they have an Emperor, but also it is a democratic state with democratic elections for the members of its Government main organ, the National Diet. If there are elections, some concept of freedom should they have. But the adoption of this western political institutions and procedures doesn’t come from a popular movement like French Revolution, but from a political and mainly economic conflict, the Boshin War. There are differences there, since, if French Revolution is a political major event, it is also a cultural major event: it changed our (western civilization) way to see the human life in society. In comparison, Japanese people has cultural traditional values deeply rooted, and the cultural meaning of the concept of freedom for them, should have to be stated searching on its relative meaning in Buddhism and Shintoism religions and cultures, much more than into the fact that they use some western political institutions…
So, it would be possible that your amazing theory could be one case of a western interpretation of an oriental story. Nothing wrong with it. In fact I enjoy the analogies and parallels you draw between Hegelian philosophy of history and One Piece. And if it’s enjoyable, I don’t care much about if it is true or false.
Coming back to One Piece, is One Piece plot a history of a movement that pursuits freedom? Is there a place for the idea of freedom in OP? I think we haven’t seen much of it. I don’t remember characters using the world, but my memory is not that good. You have to paraphrase Dragon’s worlds to make his speech match the idea, and you can see Sabo’s rejection of his privileges as a manifestation of the Spirit that search for freedom, but I don’t think he has referred to his actions as libertarian actions or something similar.
In your theory, freedom would be the main reason, the main motive, and the final objective. That could be true if it happens that the One Piece is related to it in the way your theory suggest. But your theory is pretty consistent about this hypothesis, and several elements fit well with the idea: ancient kingdom, D people, world government, Dragon and revolutionaries. So, we don’t know yet, but, yes, it could be. The idea matches with easy with all this elements of canon story.
I like the most to see D people as those human heroes required for a Hegelian view of history to drive humanity to its final realization. D people is not good or bad, but they do the things required to reach that realization, driven by the will that comes of the Spirit that search for its realization; and you can see there also the tension between Teach and Luffy, as the tension between thesis and antithesis, between two heroes of a common story that will end in the synthesis of a freedom. So it makes sense to call this history “One Piece” because that synthesis would the final reached Unity, as you pointed in the title:
everything into One Piece. Also, it is not hard to find possible that members of the actual World Government, the Marine and even the Teriubytus would end being part of the final order of things.
About it, and about Dragon and revolutionaries, I could add a little element to your theory. What Dragon and Coby would have to develop would be The State in which the freedom is possible as a condition for its members, (since it is possible to interpret Hegel as thinking that in the end the Idea reach its final realization in the form of a State that makes possible freedom).
I like those resemblances between Hegel and One Piece, enjoyable if you know a bit about both things. Pretty nice crazy theory. You have a powerfull mind, thinking wild and funny things. Kudos Lord Raileyght.