If you look around the Internet, you'll find articles, commentaries and posts proclaiming various types of technology or products are dead, that they've been replaced by some new type of technology. Even my colleagues at ZDnet are not above making such comments.
If we scan recent activity, we'll see headlines proclaiming PCs are dead/they're are not dead, mainframes are dead/they're are not dead, midrange systems are dead/they're not dead and the like. If one merely looks through the history of computing, it is clear that technology doesn't die the moment that something new is added. It continues to soldier on, doing the work it was assigned to do, for quite a long time.
Just look around. Mainframes are still at the heart of quite a number of organizations' data centers. Midrange systems can still be found surrounding those mainframes. PCs, regardless of whether configured as desktop systems, laptops or in some other configuration, are still the mainstay of personal computing.
A historical view is that new technology is added as it emerges. For a time, the growth in other forms of computing may slow or even stop while the industry explores what this new form of computing offers. It takes time to learn the limits and assign tasks to these new forms.
Most data centers are living computer museums. Examples of just about every type of computing architecture can be found quietly doing its work amidst the racks of equipment. Only on very rare occasions are established systems turned off forever. As long as a technology continues to be useful, it will be used.
So, let's welcome the Tablet, the Smartphone and other new types of computing as they emerge. Just because something new appears on the scene doesn't mean everything else is quietly escorted to the dumpster.