It's not complete competition for Garmin Pilot. With the Flight Stream box, Garmin Pilot is a 2 way communication link between the iPad and the radios, giving you a GTN style human interface on the GNS series boxes; that gives you the ability to do your flight plan and get your routing and clearance on your iPad , then instantly upload it to the radio, avoiding the push, spin, push, spin... interface with the engines running. You also get V-Airways and the ability to rubberband clearance amendments.
They haven't given out this interface yet, but I have a feeling they will. The big thing this gets for Garmin is not the increase in Flight Stream boxes (which at $1k are a bargain 'give away' in the Garmin avionics market), but the fact that they can put Avidyne out of business with it. Avidyne is all in on their slide in replacement 440 and 540 radios, but Flight Stream cuts them off at the knees for <$2k. Now I don't need a slide in replacement for my 430w to rid myself of that God forsaken interface. Now I can manage it with my iPad and/or iPhone running G-Pilot, and get my ADSB In on the cheap with my GDL-39-3D and get my AHRS input for the peripheral devices. I have a feeling eventually Garmin will come to terms with Foreflight and WingX to get that interface.