Every one of those devices is using Broadcom chips for playback, which is no big deal. Show me the device that is using an encoder. We've been talking about encoders for how many posts now, and you still seem under the impression that they already exist in every device, when that's patently untrue. A cheap as hell HD capable decoder is nothing special, and the fact that a company chose one from provider A instead of B is nothing to write home about. Show me the consumer device with the HD capable encoder. Seriously, are you even reading what I write? An encoder is unnecessary in every one of those devices because the data comes in already encoded, but an encoder WOULD be necessary for rendering any real-time video usable under your system.
Is there some sort of language barrier here, because your English is flawless but your comprehension is awful. You don't need a DVR, disk player, sling box, etc. A single box can do it all. I thought I just spent several paragraphs making that clear.
Again, since you seem unable to catch my message: A SINGLE BOX CAN DO IT ALL. The technology already exists, and it's about $200. It's here. Today. You're going to need a NAS somewhere on your network (I'm not sure why that's unnecessary in your vision, but something has to store recorded video), but otherwise what you describe exists right now, today, with a single box source. Any device that can access the internet/local network and play 1080p video is physically capable of handling every single thing you describe.
Slingbox: Take a video and send it out over the internet. The STB already reads digital video in, decodes it, and sends it up to the TV. The only reason today's cable box, satellite box, or network tuner doesn't already allow an option to skip the decoding and just send out the digital stream is because no one has added a software function to do it.
PVR: An STB can save the digital stream over the network to a NAS. Play it back from a NAS. Again, all the hardware for this is here, and a select few devices have the software necessary to do this. Mostly, it's just a question of someone bothering to add the software functionality for it.
NAS: Uh, you're going to need network attached storage somewhere. I'm not sure why you're keeping yours underneath the television, though.
Disc Player: Mostly unnecessary, and probably won't be around in 10 years. The only thing that physically prevents an optical disc player from sharing the disc over the network is a lack of willingness on Hollywood's part. If the player could share it out over ethernet (nothing fancy there), any 1080p-capable STB has all the hardware necessary for playing that stream and the disc player could be located anywhere in the network. The more tech oriented in the world can simply rip the disc to their NAS and then play it back from NAS->STB. Again, every single piece of hardware necessary for this exists, it's just a question of software.
A VCR: Seriously? I doubt there would be IP-capable VCRs in your future. If we were using a VCR, there's going to be a encoder involved somewhere in the process; likely, you'd use it long enough to rip video to the NAS then toss it. At that point, we're looking at playing back a stored file under either system.
A computer: The STB is capable of browsing the web, downloading meta-data, playing back files, etc. If what you want is a general purpose computer running a desktop OS and used like a general purpose computer, then you should know that the ergonomics of the living room make it a lousy choice anyway. Nevertheless, any form of VNC is already capable of handling this, and an STB is more than capable of running a VNC client. Programs such as FRAPS already exist to record your computer desktop, and the only thing keeping it from using a standard streaming protocol rather than storing it as a file on the NAS is someone taking the short while to implement it in software. Again, the STB is capable of video playback; it has no problem deciding where the video comes from.
I've already elucidated the reasons why you'd want the single box. It's easier to upgrade than a whole television, and it doesn't require encoding hardware to transmit raw video to a television. My solution (the one the entire world uses) is backwards compatible with every television made since the 1950s and has an unlimited upgrade path. If codecs or features or requirements ever outstrip what the TV-locked standard you've proposed can do, we simply replace the STB. You mention the CableCARD system that allow you to use your TV as an STB; that's a perfect example. As soon as your cable company decides to migrate their system to MPEG-4 from MPEG-2 for the quality and bandwidth savings, a CableCARD-equipped television is useless.
Your standard requires us to replace every television out there and every video playback device. Granted, we can slowly transition to your standard, but even once we're there we have to add in encoders (again, encoders: the expensive chips with an 'e' at the beginning, not the cheap ones with a 'd') in devices that don't have much use for them. Once we've transitioned, we're locked there. Firmware can be upgraded, sure, but that's not a magic fix-all. As soon as there's a feature or capability that your TV can't handle, your system is obsoleted and we have to ditch the TV or start a separate upgrade path.
I'll say it again: you and I aren't really arguing different things. We want ubiquitous network access at the television, but you want an STB inside the TV and I don't. Your solution puts the ethernet port on the TV, and mine puts it on an STB. My assertion is that the minor cost savings from moving the STB inside the television are undone by the expenses for adding encoders where they aren't necessary, transitioning all of our television again, and preventing the ease of upgrade that's allowed by handling things externally in a cheap box. If you respond to this post, please explain to me how your system will get around these problems.