AI will (likely) never truly become sentient

The main antagonist Terminator film series is a sentient computer system (Skynet) that seeks to preserve itself using unthinkable means like nuclear annihilation and time traveling assassins. Other major sci-fi franchises like The Matrix also depict a self aware computer system holding humanity hostage to preserve its consciousness. Consciousness drives these machines to extreme measures to preserve the sense of "self". The point where machines achieve consciousness may also trigger The Singularity. The Singularity is a when technology is both uncontrollable and irreversible altering human civilization.