Andy Cruz is someone I'm confident in possibly giving Shakur not only a very hard fight but also a loss on his record as well.
Forgetting any individual opponent, undefeated isn't a thing many fighters actually do. Shakur has the skills to outpoint people but unless he retires relatively young, his set of skills, much based on his athleticism, will fade. At that point, he does not have the firepower to hold fighters off and he will lose.
Shakur doesn't have a career, at least not a respectable one.He is not a major player in boxing since he refuses to fight top level competition.