I think Internet streaming is really just the first phase of what ATT is doing with the DirecTV NOW platform -- I think this is part of their long term strategy to get out of the business of making set top boxes. They've been heading that way with the RVU-ready TVs and tuner-less Genie clients -- but I think they're seeing it doesn't make sense for them to keep spinning new hardware every time a new capability comes out (3D, 4k, whatever comes next). Not only is it expensive to build a bunch of box variations for a single company to use, but they have to maintain stock, have techs manage compatibility, etc. It's much easier if you can go to your local store and get the latest AppleTV, FireTV, Roku, whatever box that provides the capabilities that you want as a consumer.
They've telegraphed already that they're looking at providing the capability for DirecTV receivers to switch to an Internet stream when the satellite signal drops. This "platform" that they've built would give them the perfect opportunity to do that -- currently the DirecTV NOW app connects to the service and then gets directed to the nearest Akamai cache endpoint, but it wouldn't take much for them to code these apps to pull from a data source on your home network.
There have been mentions of the new HS17 device coming out from DirecTV that's listed as a "Genie" device. I think what you're going to see is a box that will take video data off the satellites (and maybe multicast from ATT's cell network?) and serve it to DirecTV Now apps running on devices in the home. This saves a ton of Internet bandwidth usage, provides consistent quality, and will allow for interesting things in the future. If the local server is unavailable for any reason (weather impacting sat delivery, or you leave the house) they just have to code the app to switch back to an Internet video source.
