Mark Gurman of 9to5Mac says that Siri will finally arrive on the Mac this year:
Siri on the Mac will have its own pane in System Preferences and users are said to also have the option to choose a keyboard shortcut for activating the service. Like with recent versions of iOS, users will be able to enable Siri at the first startup of OS X 10.12, according to sources. If the Mac running the new OS X version is plugged into power, a “Hey Siri” command will work much like with recent iPhone and iPad models.
I’m super excited for Siri on the Mac, since it seems like the closest Apple might get to an Amazon Echo-like experience, but this is going to be interesting. I absolutely believe “Hey Siri” should work on Macs when they’re plugged in (although I would think it wouldn’t be too big a deal if it also worked on laptops running on battery, but who knows?). That said, I’m now going to have four devices potentially listening for “Hey Siri.” What happens when they all respond at once?
Also, will Siri on OS X have speech synthesis responses, à la the iPhone and iPad, or be silent, like the Apple TV? I’m guessing the former, but I wouldn’t rule out the latter.