Can quantum entanglement someday allow faster-than-light transmission of data?
Not unless the fundamentals of quantum mechanics turn out to be wrong.
If you have two entangled particles, any manipulation of one should instantly affect the other. However, for the receiver to try and retrieve any information about that manipulation, they would have to take a measurement, which would also affect the state of the particles. The receiver can not be certain what the state of the particles was before they took the measurement.
Quantum teleportation can transmit the information accurately, but it requires an additional, non-quantum line of communication that can only travel as fast as the speed of light. So quantum teleportation can’t break that barrier either.