ASIC means "Application-specific integrated circuit", so I guess that something designed specifically for a task will ever be more efficient than everything else (for the said task, hashing). Or maybe I'm wrong and ASICs will one day be replaced by something else, but I am not sure that Quantum computers could be more efficient than ASICs...
Quantum computing is based on Quantum physics and there full scale potential is yet to be seen. Bitcoin use elliptic curve digital signature algorithm (ECDSA) and we have Shor's algorithm developed in 1994 that can break Elliptic Curve cryptography by computing discrete logarithms. Shor's Algorithm can be executed on Quantum Computers only that are considered to be hypothetical but they are becoming a reality. IBM has relaeased a 400 QBits processor in 2022[1] and it is estimated that breaking a curve with 256-bit modulus requires a quantum computer with 2330 qubits[2]. With current pace we can have such computer ready in next 15 to 20 years or may be before that.
It's all about assumptions and predictions so far but there is logic in all this data about Quantum computing. Even USA government is taking it seriously[3].