The stagnation is the result of a country with a very comfortable population thanks to all that industrial growth. Comfortable people do not like discomfort and is adverse to the unkind conditions of menial labor. China will one day face the same situation. Young people will have no desire to toil laboriously in discomfort. They'll import more foreigners, there will be anti-immigrant sentiment, then factories start leaving for the next cheap labor promise land. Rinse. Wash. Repeat.