After a few seconds it struck me that what we’ll end up calling these things is tablets. The only reason we even consider calling them “mobile devices” is that the iPhone preceded the iPad. If the iPad had come first, we wouldn’t think of the iPhone as a phone; we’d think of it as a tablet small enough to hold up to your ear.
The iPhone isn’t so much a phone as a replacement for a phone. That’s an important distinction, because it’s an early instance of what will become a common pattern. Many if not most of the special-purpose objects around us are going to be replaced by apps running on tablets.