If you're serious about it, then:
Luffy finds the one piece, which is in fact only something that was prescious to Gol D. Roger, and gives Shanks back his hat (although I get the feeling Shanks will die, so then he puts it on his grave), maybe Luffy ends up with Nami, who made a world map and got rich from it, but them having a relationship is not too imoortant. Sanji finds the love of his life, and lives at an island, running a restaurant, Chopper becomes a world-famous doctor, who cures using Sakura, Usopp gets with the girl he used to tell stories to, Brook finds Laboon, Franky surpasses Vegapunk, Robin discovers the secret of the Poneglyphs, and finds what happened in the hundred-year gap, which is in fact that the marines went to extremes to het power, Vivi becomes a Strawhat pirate, while still being a queen, Zoro defeats Mihawk and is offered to replace him, but refuses. All of their dreams completed, they don't know what to do, so Luffy shouts "What are you talking about, we have even more adventures!" The series ends with the Straw Hat crew in the Sunny looking happy, like a family, an a double page spread, then in the next two pages it sooms out, then again, and one final time, so that you can see the Thousand Sunny as a dot on the son. Then, after a page of just sea, comes a black page that says "THE END" in white lettrs.
A pretty educated guess, would anyone agree?