Alright, I just got done watching the announcement, and reading a couple of articles. Some thoughts:
1) It won't replace your cable box
2) It appears that you will be able to control Live TV through EITHER HDMI-CEC or IR blasters (main evidence of this being the fact that it has an IR blaster port).
3) Given #2 above, this could theoretically open the possibility for use with Tivo's, HTPC's, -- hell, even DirecTV.
4) No mention of what it could do as a network media player for the content in your home. The emphasis seems entirely cloud- and streaming-based. No way they omitted this accidentally. I suppose that, since it has an HDMI input, it could be possible to route your HTPC's output through the ONE. And, as long as you're controlling the HTPC through other means, it is at least conceivable that you could get passthrough of your BR rips, including lossless sound. That being said, the chance of such a thing actually being possible is infinitesimally remote.
I get the feeling that, at the end of this, most of us will just be adding our ONE to the rest of the bajillion components in our AV racks, and treating it just like we treat our current PS3's and 360's...