I really thought this series would be more comprehensive, but then I went and re-read part 1 and realized you were looking for answers much as the rest of us are. I'd like to give you an idea of what I have been going through.
I don't know if you are aware of this, but PlayOn has
lots of plugins, including HGTV, Discovery, Animal Planet, SyFy, VH1, BET, the major network stations, and plenty others, so you don't have to miss out on these stations entirely. Not to mention that you praise the benefits of the Roku box, and totally leave out
Amazon VOD! Yeah, it's not free, but they have boatloads of content from all of the major cable channels at a reasonable price, and if you buy a TV pass, it gets even cheaper. They also have lots of free content, though the vast majority of it is crap. If you are an ultra heavy TV watcher, then Amazon VOD might be too expensive, but for the casual watcher even $30/month can purchase a good amount of content. For sports, you can even stream live sports from MyP2P.eu, which I have been using for 2 years to watch NFL games outside of my home market (although not in HD).
I thought maybe you would try a solution that combines PlayOn with plugins, Netflix, and Amazon VOD, which is a good and cost-effective combination that has lots of great content. The problem is making them all work together seamlessly, and I don't know if any of these boxes can do it. For example, PlayOn has a Netflix plugin, but it sucks, since you have to manually add selections to your queue. The PlayOn plugins don't always work. (The Justin.tv/Ustream.tv saga is turning into a Greek tragedy at this point.) Sometimes they get updated, and it breaks the old one, or a new one is released without your knowledge and you are wondering why your episodes have stopped updating. You really have to stay on top of these to make them work.
For WAF purposes, I'd like a box that has a Netflix app that displays it like the X360 does (menus, recently watched, which episodes watched and the percentage viewed, etc), have PlayOn as a separate app to watch Hulu and plugins, have the ability to add services like Justin.tv and Clicker, and play all of my other media content. I am currently using a MediaSmart EX90 with the PlayOn add-in to stream everything to my TV's, but the WAF is low because the media frontends are all different (PS3/X360 in one room, XBMC on Xbox1 in another, etc), so my wife would have to learn all of the menu commands per room. I really don't want to have to buy a set-top box for every single TV in my house, but if there is one that can accommodate all of these requests then I'll consider it. Admittely, I have little experience with the ROku box, so maybe it can do all of this.
As far as Netflix or Hulu cutting a deal with the major networks, the chance of that happening anytime soon is zero. The major networks hate Hulu, and will never allow it to be seen on televisions, which is why it has been banned from the Ps3 and Boxee. Not to mention that when Comcast purchases NBC, they will never allow content to be streamed to a STB, as they will have a major stake in keeping the cable tv monopoly going. Everyone says that ala carte won't work, but I can buy high quality, high production value, zero commercial 'premium' channels like HBO or Showtime from my cable provider for only $10. And that's the price that the provider charges. Imagine if you could get these channels directly from the source. Imagine a $50/mo cable package that included Hulu, Netflix, 30 monthly Amazon VOD downloads, two premium channels, and ESPN. Bring your own bandwidth and STB.