Registered acc, just to join this epic thread. Good theory, with just some flaws.
1. History pattern - totally agreed.
2. Idea that Luffy will destroy Marijoa and it will also fulfill prophesy of mermaid - nice idea.
3. Idea that different seas will connect and it will fulfill dreams of many crew members, and will be named One Piece - good one.
4. Idea that ancient weapons can be used in good way (like controlling the weather and so) - epic one
5. Idea that Luffy will destroy two spots on red line - I think it is going vs Oda's way of telling story, because things and deeds don’t repeat themself on the same level in this manga, as long as story keeps progressing.
6. Idea that it will fix everything - also not the best one, and in this thread you already discussed why.
Ok now let me tell you few thoughts, that came by, while I was reading this thread:
Your part, about mermaids prophesy and Marijoa - makes a lot of sense. But lets look why Marijoa has to be destroyed (except the fact that Tenrubito are assholes).
Tenrubito live in a somehow secured place (but not unreachable), but everyone knows that you should never hurt one. Why ? They are terrible warriors, as we saw. Why do people fear them ? It looks like they have some untouchable power, probably mechanism, that allows them to control everything, not caring about their own strengths or powers.
There are two things, that keep bothering me in this story, and about which you totally forgot.
1. One piece world structure. (Red line and grand line). There is no way that they are look natural. Ye you can say that it is made so, because Oda's left foot want it, but is it the real reason ?
2. Why Ponegliths can be found only on Grand line, and how they where transported to so many different Islands ?
I'll tell you why:
I think the enemy of the AK (ancient kingdom which I think was called Raftel) was far more sinister and must have done something rotten enough to win that would antagonize the world. And I'm pretty sure it might have to do with the sort of social structure it led to with the tennryubito being on top of everyone.
I've been wondering though how the fvck did the WG manage to erase a 100 years of history. It makes more sense if it's limited to a country, but they literally wiped out the world history. Unless they did something horrible like slaying 90% of world population, …, it sounds impossible
Unless, like you said, both red line are grand line(along with calm belt) were somehow artificially made. Though I have no idea why would someone built them in the first place or how the hell they did it. The possibility is there though….
As I think, Ponegliths are indeed traces of ancient civilization. But they weren’t transported. They were created each on a Island, that they are now. I think, that whole civilization on their inhabited islands, where transported to artificial terrible conditions, that nowadays are named Grand Line, in order to be vaporized from history.
I think, that devises, that made this possible are still in the hands of Tenrubito, and probably located at Marijoa. I think the reason WG hunts ancient weapons is to keep Tenrubito's power unrivalled.
And yes I think, that in last ark we will have epic world war, because we have Dragon's army and ViVi already, and if Luffy just destroys red line they are less likely to be involved.