The “grand criminal conspiracy” in GTA 6 is just the FIB vs. IAA feud that never died (theory)
In the official GTA 6 synopsis, Rockstar states that after an "easy score" goes wrong, Jason and Lucia find themselves caught up in a "criminal conspiracy spanning the state of Leonida". Bonnie & Clyde, drugs, cops, the lowlifes of Vice City. We know what it will be. But I can't stop thinking that this "conspiracy" is actually a direct continuation of the cold war between the FIB and the IAA. In GTA 5, the FIB and the IAA were literally killing each other over power, information, and who controlled what. If you look at Steve Haines, Dave Norton, ULP, the Mr K