Honestly Solid theory. Anyways while I was browsing through the internet I came up with this dude named Drizzt who made some videos about how he views post timeskip as like le downfall of one piece, while I didn´t fully watch it I can say that there is some points that I simply don´t agree with (mainly about how the antagonist of FMI shouldn´t be an actual physical threat but more so a psychological/political one & the fact about how he saw Sanji vs Queen as..character assasination? ) whie I do think his videos come from a sincere place, I can´t let my word be gospel as I haven´t even fully watched it so I wonder if you would be interested in knowing about that.
I can see why people view the New World/Post Time Skip as a downfall of the series.
The art, particularly recently, is a lot rougher, and so is the pacing.
But, I've said before, and I still maintain, that the New World/Post Time Skip has actually been setting up the end game of the series. Vegapunk, IMO, laid it out most cleanly: at this point, it's all about the Ancient Weapons and the One Piece itself. The Ancient Weapons can literally end the world, and the One Piece will determine who rules it.
I believe each Ancient Weapon will be dealt with before Laugh Tale. And when you view the New World from this lens, shit makes way more sense as to what Oda is building up to.
Fish-Man Island set up Poseidon, and the Reverie continue Shirahoshi's journey as a character. Like Vivi, we now have an ally that fully understands the Celestial Dragons on a ethical level.
Alabasta, Water 7, Thriller Bark (through introducing Kaido/Wano, in the Pre Time Skip, and Wano continued this plot-thread, revealing that the Ancient Weapon the world would fight over will be activated when Wano's Borders are destroyed.
Egghead furthered both Pluton and Poseidon, along with Uranus, through Vegapunk's declaration that the Ancient Weapons can end the world, or at least do serious damage to it. It also furthered the Ancient Weapon plotline when it came to Poseidon and Pluton, when Carbiou was taken by Van Augur and Catarina Devon to Teach to reveal their locations.
I believe Shiki has Uranus, and can make it float, but cannot power it, and we see him use his powers to both levitate Uranus, and Bege's ship, here, in Chapter 594
If the final arc really is a giant race to fight over Shirahoshi/Pluton, and then Uranus, I think the set up has been worth it. If the Ancient Weapons honestly change the game, we can see really serious fights going forward, and more serious situations in general.
The New World/Post Time Skip will always be under Pre Time Skip for me, but, I think the Final Saga can really build on the New World to become a fantastic ending, that will make the previous section of the New World look a lot better.
Oda's set up a lot of good plots, he just needs to execute them, and, my hope is that Imu's descent is really going to kick things off.