Since the Nika lore comes from Elbaf, we'd probably end up seeing some Nika wank fest at one point lol. I doubt Usopp will get anything significant, but I hope he'd get some character development
With that said, there are things that could be interesting as well
- We know Shanks was in Elbaf and the giants know him, so it could be interesting Oda drops more important infos regarding Shanks / Red Hair pirates
- We also know that Saul is in Elbaf, so we might get some info dumps between Robin, Ohara and him(maybe even Kuzan if we're lucky lol)
- We also know Kid was defeated in Elbaf, so maybe we could get more infos about them, maybe even a reunion with the Strawhats at one point
- There is even Big Mom who had a story with Elbaf
I also find it hard to believe that they'd go to Elbaf without having any hint on the location of the last road poneglyph
But that's if we're too optimistic about it lol