Theory on the future of Android's design language
Based on the KitKat pictures, it looks like Google has decided to make the Navigation bar transparent.
Transparent is one way to think about it, but another is to say that they've removed the bar and decided to place the buttons onto the actual screen real estate instead (effectively increasing screen size)
I think this is merely the first stage of the end goal to completely remove the dedicated navigation bar area. We're going to see future versions of Android and future versions of apps moving app-specific UI elements into the navigation keys themselves. Once an app has "back" defined somewhere within its workspace, only home and the multitasking button remain. I think these will be replaced by swipe actions (e.g. swipe up for home, swipe up and hold for multitask) and Google Now initiation will be moved to the first page of the home screen.
What do you guys think?