??? Vietnam has nearly twice South Korea's population (and less than Japan's) and of course, it also has scale, as South Korean businesses in Vietnam have shown repeatedly.

To boot, Vietnam has no immediate internal political threats (eg, compared against China's separatist movements by ethnic minorities in Tibet, Uigher, Inner Mongolia) or no potential regional geopolitical/territorial conflicts with neighbors (eg, Phillippines, Japan, India, etc), other than China. And, most importantly, despite having fought a war half-century ago, America's diplomatic and trade relationship with Vietnam is far less hostile -- it's in fact quite amicable -- than with China.

>> ... but the supply chains will remain plumbed through China for a while.

That's inevitable only b/c of Apple's political clout and relentless lobbying here in the US. I was hoping, while I was no fan of Trump, Trump's trade policy would at least partly address this, but oh boy, how quickly he caved in before Apple and dished out tariff exemptions.