On a PPP basis, China is already the world's largest economy, whilst your last paragraph is a complete non-sequitur.

I first encountered "Communist China" living in North Yemen in the early 80's when they were doing the navvy work building Tank Grade Roads from the Saudi Boarder down to the Southern boarder, I had seen the Koreans do similar projects a few years earlier in Saudi; Western Firms do the Engineering, Asian firms do the navvying but learn how to do the Engineering. When I went back to Saudi in the 90's, the Koreans were doing the Engineering, and the Indians the navvy work...

When I did my undergrad in the mid-80's, my International Economics Prof explained how by about 2030, China would inevitably have the largest economy in the world, to be over taken by India around 2050 - it all boils down to demographics.