The question you should really be asking is: where will manufacturing for the west take place in ten to twenty years? East Africa is more plausible than China.
It is easily possible to expand to parts of china that is not in the industrial zone, since only 10-20% has been turned to sweatshops. And no, those shop's wages are nowhere even close to being high enough for multinationals to consider moving, since it is not Shanghai citizens that are doing most of the work, but the migrant workers. Plus, multinationals like iron fisted government that has control of the whole country instead of the weak, democratic or non-existent leaders.