This company may very well outsell the iPhone in China. Since the phone is little more than a lower priced copy of the Apple product, it may very well outsell the iPhone in Asia. But there is little hope of doing that in the Americas. Apple is a trusted name in North America and Europe and that's not about the change.
Xiaomi's new smartphone, a cheap knock-off with an almost identical design as Apple's new iPhone 6 and iPhone 6+ hasn't a chance at outselling the Cupertino Giant's iPhone, 2015 or any other year. Apple has the smartphone market cornered and is the producer of the most popular smartphone in the world. The Xiamoni knock-off won't even be a blip on Apple's radar for 2015.
No, the new Xiaomi smartphone will not outsell Apple's iPhone in 2015, because the iPhone has too much brand recognition. I do not even know who makes the Xiaomi. Until that company gets some name recognition, they are always going to lose market share to the big bad Apple, and their mighty iPhones.
The new Xiaomi smartphone will not outsell the Apple's iPhone 6 and 6 plus in 2015. The simple reason they won't is the sheer size of the Apple econsystem, it's just too large for anyone to over take them with a single product, no matter how good that product is. For Xiaomi to be a success in the smartphone market they will need a series of successful products to overtake Apples flagship phones.