What if...

[Bob2000]

What if there was an episode where Conan goes against the Yakuza? Or maybe the BO is actually the Yakuza?

[Wakarimashita]

The BO is clearly inspired by the Yakuza (their mafious nature, Vodka calling Gin 'aniki'...).

[User 4869]

BO are regular yaguza, if only DC did not become so famous and Gosho has to bring them back to move the plot instead of just have excuse to have Conan turn to a child.

[GreatDetective]

What if there was an episode where Conan goes against the Yakuza? Or maybe the BO is actually the Yakuza?

Yakuza did made an appearences in Detective Conan, in the Sonoko's Red Handkerchief case (chapters 541-542-543).
As for the BO inspiration, I think Gosho used both real life organizations (mafia, camorra, 'ndrangheta, yakuza, etc.) and fictional ones (Arthur Conan Doyle's Moriarty gang). He may even have partially based the BO on his own organization in Magic Kaito.

[Borealis]

Changing the question: What if Conan has to work with the Yakuza to bring down the BO? (Because the BO is now a too strong "concurence" for the Yakuza)

[Dwalin]

Changing the question: What if Conan has to work with the Yakuza to bring down the BO? (Because the BO is now a too strong "concurence" for the Yakuza)

Conan wouldn't do it. The Yakuza kill people, and Conan is obsessed with the idea that killing is wrong, to the point that he doesn't see the difference between murderers who act out of despair and have extenuating circumstances and those who don't.