100Kbps/subscriber is around 200Gbps for Comcast. And that's just 100Kbps! Netflix is going to keep telling their customers they're getting a suboptimal HD experience (and they'll be right!) until the average stream gets somewhere near Blu-ray's ~20Mbps. Maybe half that if you think codecs are going to get better, but by then 4K will be winding down the pike.
The point is that for Comcast and Verizon, there's no end in sight: A few more ports connected in a few more data centers isn't going to do more than make a few subscribers slightly happier for a few months.
It doesn't have to be dedicated, just bustable to a reasonably large number of subscribers at a time. Netflix will prefretch data and a small amount of burstable bandwidth goes a long way in viewing quality. This isn't about letting everyone stream SuperHD content at the same time, this is about relieving some pressure around the average bitrate (somewhere around 1900Kbps)
The point is that for Comcast and Verizon, there's no end in sight: A few more ports connected in a few more data centers isn't going to do more than make a few subscribers slightly happier for a few months.