The PC era is not dead any more than the refrigerator era is dead. But as long as it does not mean anything to proudly display a Windows logo, Windows itself is endangered.
It has already happened: Apple has captured the hearts and minds of the technology-using public, even those who don't actually own Apple products. It does not mean anything to own a Windows PC. If you wear that fact on your sleeve or on your T-shirt - "I'm a PC" - you may as well be hoisting a cardboard sign that reads, "I'm a refrigerator." But it does mean something for these people to show their Apple logo. It's the reason why shell cases for iPhones have holes in the back, and those for Android phones don't.