I think in the Elbaf arc for some kind of reason the Giants will make Ussop the commander of their most OP unit or make him their leader so in a way Ussop might become a significant threat to the World Government
I think hes gonna unlock some form of basic conquerors haki and impress liking the leader of the giants. After this I think liking will give him controll of an army with over 8000 men
Since san Juan wolf already has the fruit that makes you able to grow, Usopp may get the hito hito No mi model giant, allowing him to transform instead of just being a giant, and Maybe A human giant hybrid could maybe be a Buccaneer