Much of the coverage about the new DIAL multiscreen protocol effort has focused on how the technology is a potential replacement for Airplay (which, by extension, would also mean it's a replacement for Miracast).
Well, here's the thing: DIAL and Airplay/Miracast are really meant to do different things and, in the end, devices like connected TVs will support both DIAL as well as content-throwing protocols like Miracast.
In case you're stil not convinced, let's look at what each is meant to do. As Janko explains, DIAL is more about using your second-screen device to launch apps on your first screen. The real value in this is DIAL can initiate a video play (like, say, on a Netflix or YouTube app on your TV) by launching the app and then sending a URL to the TV so the video app can access the video file directly. This essentially takes the tablet or second screen device out of the equation which is, in reality, a good idea given a second screen acting as set-top or video servers can suffer from a multitude of issues such as bad Wi-Fi, low batteries, or what-have-you.
And where DIAL really differs from Airplay/Miracast is that with the latter two technologies, content is streamed from your second screen device to your first screen. Now, Netflix and Google both realized streaming directly from the cloud to your TV is probably a better idea than having it stream from your tablet (given the reasons identified above), but that does not mean there are not use-cases where you would want to mirror or "throw" content from your second screen device.
Think gaming, personal videos or even something like a powerpoint presentation. These are all unique instances where Airplay or Miracast is actually a better technology and one that DIAL will likely not be used for.
So, in the end, let's stop calling DIAL an Airplay replacement. It isn't. It's just another technology that will do one or two things - but not all - better than Airplay does.