Aesop Usopp's Fable! Hear the tale of the legendary God Usopp!
Seriously though it would be bitterly ironic if Mr "Im gonna die alone as a brave warrior of the sea" and "Im the most useless/expendable one" is the only survivor but weirdly bittersweet too.
He finally becomes the captain of his own crew, a God and a hero. As a sole/soul survivor.
I miss pre TS Usopp so much I wouldn't mind this, I love his relationship/storyline with Kaya and his little crew of buddies on Syrup Island. His backstory hits a little too close to home for me too.
I want the best for him ultimately when the story ends. I pray Oda delivers for him ultimately, especially in this arc of all arcs ofc.
If Usopp was narrating the story of One Piece the whole time, that would be so meta with the whole Joyboy story in the story, One Piece world having comics which turned out to have real life equivalents in the story (Germa in the OP comics exist for real in the OP world, not sure about Marine Sora yet but would make sense) and thus the ultimate "Laugh Tale" or something.
Oda could cook something amazing with this. Maybe he could fake all the SHs dying in the end but have them show up much later, kinda like a Sabaody Incident 2.0 or Fairy Tail Tenrou Incident too especially?