As you can see in the video below, the graphics artists has tried to solve Apple's screen-to-body ratio puzzle by shrinking the home key, while keeping its signature round shape, plus the bezels have been shrunk all around in general. The seemingly improved screen-to-body ratio would be a welcome change, and the mirrored finish on the back suggested a new premium material for the housing.
The iPhone 7 concept is also equipped with USB Type-C connector, and a 16 MP camera with optical image stabilization, though both of these are unlikely to materialize, knowing Apple's typical upgrade schedule. The iPhone 7 will likely keep the 12 MP sensor from the 6s, perhaps only adding an OIS system to it, plus the trademark Lightning connector seems to be here to stay for a long time. Another improbable development is the AMOLED display listing, which, according to analysts, will be a wishful thinking for an iPhone at least for the next few years. That's still a concept, though, and beautifully rendered at that, so anything goes before the iPhone 7 becomes a reality.