The quantum threat to Bitcoin mining via Grover’s algorithm appears limited by physical and economic constraints. Quantum miners would face disadvantages including longer computation times, limited parallelization benefits, and substantially higher capital costs. Research indicates that quantum mining would remain economically impractical even with significant advances in quantum hardware, as the theoretical speedup from Grover’s algorithm is insufficient to overcome the efficiency gap and lack of parallelization compared to specialized classical ASICs. This suggests mining security may prove significantly more resilient to quantum advances than transaction signature security.

If quantum mining does become viable, however, there’s the potential for correlated fork events if quantum miners adopt aggressive mining strategies, which could lead to attackers with less than half of the network's hash rate being in a position to execute 51% attacks. And if quantum mining becomes the dominant means of mining on the network, the quantum superlinearity problem could drive extreme centralization, concentrating mining power among just a few operators.