Luck is what they will need. Epic marketing failure in the making. My parents and there friends have trouble enough with new software iterations. Many people won't even know there is no headphone jack until they unwrap this thing. Then they will first accept it, until they end up on vacation, a business trip, a plane or in the train without the dongle. And suddenly all that beautiful music, all the movies are kept safely away from them in a stylish box. Big annoyance. In the US this will probably not happen. Apple is so dominant here that accessories are sold at every street corner. But internationally Apple is often chasing the market leaders. Apple accessories there are scarce - especially outside of bigger cities. This has a big potential of a blowback.
Disclaimer: I have owned almost every iPhone since the original iPhone, own an iPad and am on my third Macbook. I wish Apple no harm at all. But when I see the company drive onto the edge of a cliff I will not expect a wonderful takeoff. This can crash and burn badly.