Successor State + Carthage 'What If?' Question

[Cyrus]

, although from military point of view, after Carthage they didn't face an equal enemy that could threaten their very existence until the barbarian invasions of the late 3-rd century and onwards.

that is untrue, you are forgetting the parthians, the sassanids, the dacians and the ptolies were all very strong powers, at their peek during roman expansion, though i'm not shure about the ptolies.