Samsung's recalling 2.5m phones and requires owners to send them in, upon receipt of which Samsung will forward replacements.
DHL/FedEx/UPS et al are supposedly saying "Transport damaged lithium batteries? Not a chance"
Square 1...
What makes you think the faulty units will be shipped all the way back to Korea? The logistics cost would be astronomical, and for what gain? Harvesting a processor or some other fancy bits? The 'new' Note7 has changed it's internal architecture, so you probably can't swap things over easily. But, that's besides the point. Point is, it'll cost a serious lot and be a major hassle, shipping a couple million units back to the mothership for little, if any, gain. They'll be tossed on-site, crushed properly at re-cycling centres. Which, incidentally, will also cost them a fair deal of money - but far, far less than shipping them home.