Pretty convenient how possible Ryuma clone, Roronoa Sorrow reunites with the group the moment after Vegapunk "mysteriously" disappears.
Surely Kuma's backstory will have some relation as to why Kuma tested Zoro back in Thriller Bark. If Zoro is a clone, this significance would give Zoro possessing Kuma's lineage factor more depth character wise. Perhaps the reason Zoro's lineage in Wano was passed over, was due to it only accounting for a percentage of Zoro's total lineage factors.
Let's assume Zoro will achieve self-actualization of his lineages by the time he becomes King of Hell and accomplishes the dragon slaying feat over the capital. We don't know how many lineages Zoro has, therefore we can't unlock Zoro's "backstory" until we have some semblance of what each lineage means to the story. I think we can cross off Roger Kaidou, Whitebeard, Oden, Ryuma, King and now Kuma's significance towards Zoro's lineage.
What character's lineage depth are we missing, just Mihawk, Dragon, Shanks and maybe Xebec. For this final saga it just so happens that these characters story points are the only ones remaining out of Zoro's final lineages. I have this strange feeling the remaining characters are all interconnected and if you include Kuma, the points of the story which have had "guides" or surprise appearances were Dragon, Kuma, Shanks and Mihawk. With Dragon and Kuma's strong relationship with Vegapunk, I could definitely see Shanks and Mihawk playing a part given their auspicious appearances to test or help our crew.
With the above logic, I think we will have a standoff against Blackbeard and learn more about Rocks D. Xebec after Egghead. The remaining Zoro possible lineages seem like some sort of end of story plot to encompass the entirety of One Piece.
Zoro being a clone is the final curtain of One Piece. Who knows, maybe Zoro is the secret final boss.