The only way I see this happening is if the EU changes their rules and says all cell phones have to use USB-C and no adaptors are allowed. Right now they require micro USB and allow adaptors, so Apple just gives EU customers the little micro USB to lightning adaptor.
I do think we will start to see Apple switch the power supplies over to using USB-C and we will get USB-C to lightning cables. I'm not sure that this will happen with the 6S though, I'm thinking maybe with the iPhone 7, or maybe the iPad Pro if it is real.
I do think we will start to see Apple switch the power supplies over to using USB-C and we will get USB-C to lightning cables. I'm not sure that this will happen with the 6S though, I'm thinking maybe with the iPhone 7, or maybe the iPad Pro if it is real.