Yeah, for households that watch a lot of TV, and also use the internet a lot otherwise, a streaming cable TV service like DirecTV-over-IP or DirecTV Now could mean that they exceed their data cap. But for many folks, it wouldn't be an issue. For years, I've had a 1TB data cap with either Comcast or AT&T (I've used both for home internet) and I've never come close to using half that much data in any month, despite the fact that I stream 85% of the video that I watch. (The rest is OTA TV.) I also stream music, am on the web a lot, and have to upload and download graphics files for work. But I don't do online gaming, I don't download video torrents, and I don't often download huge software updates.
Of course, data caps for DTV-over-IP won't be an issue for those who have AT&T home broadband service because AT&T will waive the data cap if you bundle their TV and internet service. Having a modern, less-expensive-to-install TV platform to offer their home broadband customers is part of the strategy behind this upcoming DTV-over-IP service. I suspect they'll also employ
multicast ABR technology on their network and in either their internet gateways or the C71 boxes too, in order to reduce network traffic from popular live TV channels.
Right now, when someone signs up for AT&T Fiber home broadband, they can choose between DTV satellite or the old Uverse TV system (which has been rumored to be on its deathbed for a couple years now). Once the new DTV-over-IP service launches, I suspect it will be the only choice offered for bundling with AT&T Fiber (although perhaps satellite will still be available for installation if the customer insists on it).
AT&T Fiber has really been expanding over the past year or so. My house had been served by what used to be called AT&T Uverse (fiber-to-the-node up the street, then the rest of the way over DSL phone lines) but they converted my street to all fiber last fall. My Mom (in another state) called me yesterday to say that a door-to-door salesman informed her that AT&T Fiber was now available there. (About time, as AT&T never even offered so much as DSL at that location all these years.)