Designers do this stuff because they have ideas about how devices and interfaces can change and they explore those ideas. It doesn't seem to me that Johnny is making claims about inside information. He's using his visual talents to create mockups of what might be possible in the future.
The medium is different, but the process isn't any different than sci-fi writers setting stories in the future or me making UI wireframes for an application. It's just ways of exploring what could be done.
The last point is to realize that this is most likely just personal portfolio work. Some of us have github profiles and others have PSD's. Just think about the exposure Johnny is getting out of this and how it might get him more work in the future. That's the best reason for him to make this.