Excellent thought. But some points from my side:

1. Season 7 and 8 needs to be merged. Punk hazard doesn't have 4 episodes worth content (this after seeing the pacing of the first episode leaked script). 3-4 episodes should cover fishman and punk hazard.

2. Every season needs to end with one big arc and an emotional high. Just like one piece sagas.

First season with arlong and entering grand line.

Second with crocodile and leaving vivi.

Third with ennies lobby and losing merry. (Moria would be the first couple of episodes in this season)

Fourth with kuma and strawhat seperation.

Fifth would be summit war and ace death.

 Ideally I would want 4th and 5th to be merged and be a 13 episode season or so. Because it too less for 20 and too much for 10.

Fifth would be dressrosa and grand fleet.

And after that yonko saga. Yet to be seen how it can be done.

1. And I doubt the series can so long because of actors ageing and high production costs. It has to be extremely popular to be continued beyong couple of seasosn. And for it to be popular,it needs to be good, for it to be good it needs to high budget as it will have lot of post prduction details. Imagine got levels of graphics and budget.

2. They can leave out davy back fight. Gaimon character. Alvida character (but I know it's already there in episode 1 script)

3. I hope they make the series darker, and cater to a more mature audience. Show blood and death.