I'm calling it now: this is for augmented reality displays and similar. You want an RTOS for loss and predictable latency. And current GUIs aren't really suited to 3D environments you can walk around inside. This is Google's next Android, with a low latency rendering pipeline for the next generation of mobile devices.
Wouldn't that be nice after Google has affirmed again and again that Java would be the only supported way to develop Android apps, even though they keep Dart funded internally... Hey, I'll bite. Let's see.
Brian has been talking about how much he hates Java, its programming model, event loop, and everything else about it for many years, to anyone who will listen. Tastefully chosen for the augmented reality, self-organizing, and real-time use cases, the building blocks: UI, rendering, and app framework, all this looks like what he would create for the next generation of connected devices, of which phones are just a momentarily important example. Without Andy Rubin shoving a tech stack down his throat, I would add. I am somewhat disappointed by the DART choice, but overall really excited to see what this turns into. Great that it is open source for now, but this is Google, so you know where that will go.