Will quantum communication threaten traditional communication once it is successful?

No threat. Quantum communication is just encryption.

Quantum communication is mistaken for superluminal communication, but it is actually only encrypted communication. This has disappointed many people and can only be said to be false. There is no theoretical support for superluminal communication at present, and superluminal communication is impossible.

At present, the United States leads in quantum computers, and China also has research in this field. Once a qubit is cracked, it is easy to crack the eavesdropped information. The threshold of quantum communication is slightly lower. As long as quantum communication is done well before the United States successfully develops a quantum computer with strong computing power, it is not afraid of leaks. Quantum communication is useful for military and banking, but basically useless for civilian use. In addition, quantum communication can only ensure that the communication channel is safe from eavesdropping, but it cannot guarantee that it will not be leaked. If the terminal and repeater have problems, quantum communication cannot be solved.