No lol. Its the same concept as villains like Doflamingo, Big Mom and Kaido all believing they could/would be Pirate King before they all lost. Blackbeard has a bit more depth in his history and Im sure he'll be tied to the end of the series, but I highly doubt hes the last fight.
Hes human, is relegated to powers of devil fruit, and has a goal that involves unseating the current power of the world, which clearly requires getting One Piece according to Roger.
So unless we are insinuating Oda will not let Luffy become PK, I have absolutely no reason to believe BB is the FV, especially not after this chapter