There still remains enough old growth to continue running for about 20-30 years at the previous production rates. When logging of most old growth was curtailed some mills closed and some retooled to process the only timber left available.... small diameter second growth. 2nd growth is fairly uniform and defect free and thus can be processed by robotics.  It wasn't automation that put the workers out of a job per se. It was the end of old growth logging which required many highly skilled laborers.