Throw enough money and you'll make a Japanese speak Mandarin. Throw enough money and you'll convince an Indian to learn Mandarin.SK/Japan/Taiwan and to certain extent China demographics will not get better and they may not attract people from other cultures.
US still attracts best of Asia. and EU attracts best of nearby countries. so there will be shortage of skilled manpower if Asia tried to build entire supply chains.
Past pages in this thread had posts about how China was recruiting talent from Taiwan, Japan, South Korea and elsewhere.
And China's own vast pools of freshly minted students are going to help a lot. Money is King.