Bb has always been set up as the battle for pk. He isn't set up as the FV because beating bb just knocks out a yonko while wg still would stand as the biggest villain in the story. The FV is someone in the WG because the WG has to be taken out for the world of op to be really saved. BB will be the perfect fight for pk but he isn't last villain material unless he somehow manages to gain control over the wg.
I'm just confused by all these BBP = FV talks, if they're FV then who will the SHs fight for the OP & PK title?
Will it be a walk in the park like Roger? ( after he got Oden )
Or will they fight another group? But :
Marine HQ = far too strong, even for Post Elbaf SHs, especially with 7 Seraphims
Edit : fuck, they're not fit for the "Pirate King" title fight in the 1st place too, just like the Gorosei & HKs
Cross Guild = far too weak, the only feasible fight = Zoro vs Mihawk
RHP = maybe, but with the existence of Shamrock this becomes really questionable
If this happens i doubt it'll be a serious fight where Luffy beats down & rubberize Shanks in G5, and Zoro inflicting lethal injury on Beck
HKs = doubt SHs will face them again after Elbaf, arguably not fit too for the PK title
Gorosei = too soon to be defeating them Post Elbaf, also arguably not fit for PK title fight. All 5 of them combined is too strong too
So that leaves the BBP.
Yes they have the intel on Pluton & Poseidon, but this may be the thing that forces Shanks to stop him, cause if the BBP even gets 1 Ancient Weapon, the power gap becomes too big.
The BBP is already much stronger than RHP with Kuzan, it'll get much much worse with an Ancient Weapon.
Plus, BB seems like the perfect opponent to force Luffy to reach Shanks/SoyBoy CoC lvl, to fight Imu, as he's the one who can completely turn off Luffy's DF, which will force Luffy to focus using & strengthening Haki.
Even Warcury's roar with powerful CoC couldn't turn off Luffy's DF ( remember Jinbe hyped Mars' CoC ).
The only other candidate to turn off Luffy's DF is Shanks, who pushed GB out of monster form with CoC, although GB was caught off-guard ( same with Gorosei with SoyBoy's CoC ).
But again, Luffy fighting Shanks is questionable with Shamrock's existence.
Plus, IMO the main reason of Garling & Shamrock being such powerful CDs in the WG is probably to extend Oda's Shanks wank into the Final War/Last Arc.
( remember Oda said Shanks resembles himself the most out of all OP characters, and is likely one of his top favourite characters ).