I'm sure there's already a considerable number of Chinese sourced components on every BMW, maybe not first or second tier, and maybe disguised by the fact they are European OEM's, but they may well still either source, or manufacture, from/in China.
Also the point someone above made about the X's and Z's being made in the USA... not wishing to offend, but most people in Europe really don't consider Americans to be that great at designing and building quality product either - Made in the USA is hardly a stamp of quality, but that doesn't mean to say the vehicles that roll out of Spartanburg are any worse than those from the European plants.
So many aspects of the manufacturing of cars these days have been completely de-skilled anyway, so long as the design and processes are set by people who know what they're doing, there's not a problem - doesn't matter the nationality of the people pressing the buttons.
Chinese auto manufacturing has come a long way in recent years, with the input the rest of the world's car makers HAVE to have in order to sell their cars in the BIGGEST market in the world (sorry for the butt-hurt america, but you're not the priority anymore), the Chinese are only going to get better.
Also, if China really wanted to copy BMW's they can anyway, just doing it this way BMW gets to make some profits out of it.
... if you can't beat 'em, join 'em.