Like LLRL is a good cool down arc after a long arc, and it helps set up Usopp feeling worthless and that they need a shipwright. It absolutely has a purpose, and if done as a episode I could see it happening maybe? But its generally not popular with fans and treated like canon filler (people would much prefer G8 be real) and the anime didn't help by doubling the davy backs. But I could see it as a episode.
But as a season finale? Zero chance.
And as a season premiere, coming back in on a weird goofy ass thing? That's also pretty rough, and would require the entire third season be SKypeia which... I also don't see happening.
So you'd have to do it in the middle of a season. So the only way to make that work would be a super short skypeia, then LLRL, and then, what... half of Water 7? Or a super condensed Water 7?
They already put in the Noland story, and Skypeia is a visually unique place and if done in 3 or 4 episodes instead of 2 years I can see it working as side trip. But I can't imagine any scenario where they make it an entire season. And spending half a season on it, to then do a half of water 7? Unless they're renewed for seasons 3 and 4 at the same time guaranteed, or get longer seasons, it just doesn't work.
Maybe, maybe if they do Skypeia as a special event movie, to help lessen the gap between seasons, rather than as part of a season?
It'll be easier to judge after we see how they handle season 2. If that cuts Little Garden and how it trims down WHisky Peak and Laboon. How well does Alabasta condense to 4 or 5 episodes, does the farewell to Vivi even work if you've only known her for 6 episodes instead of 2 years, etc. Really hard to judge how the rest will function without seeing that.