So hey, I've seen a theory floating around that I actually found kinda interesting due to how unlikely it seems:
What if Violet is Fujitora? Again, I know this sounds really out there, but consider one thing: "Fuji" refers to the wisteria flower, whose colors include
purple AND
violet! So now there's a chance that either the blind man OR the woman currently seducing Sanji could be the new admiral (personally I'm still betting on the blind man, though
).