The problem is that even with N years until we reach that point it seems likely that it would take 2*N years to build the proper safety mechanisms because at least currently capabilities research is racing far ahead of safety research. Of course we have no way to know how big N really is and recent results like GPT-4, Llama, Gato, etc. have shifted peoples timelines significantly. So even if 5 years ago people like Geoff Hinton though this might be 30-50 years away there are now believable arguments to make that it might be more like 3-10 years.