No, this is not true. Before this conjecture was proved, you could just assume it was true and see if it would lead anywhere. People already do that with the GR

No, this is not true. Before this conjecture was proved, you could just assume it was true and see if it would lead anywhere. People already do that with the GRH. If it did have consequences, people would use the resulting algorithm regardless of whether the conjecture was true, because we believe to be almost certainly true. But even if you didn't believe that, you could see if the algorithm was effective by applying it to real world instances.