There’s more to the shock of China's declining population than just births, deaths and marriages. Chinese GenZ and Millenials are choosing career over kids - or choosing to “lay flat” or “let it rot”. The two most educated and affluent generations in China's history are making choices that are changing the economy and challenging Beijing's policies - but they're now facing historic levels of unemployment, just as a record 12 million Chinese college students are about to graduate. Jasmine Tse…