I have thought about similar set ups but not as complex. I would still want other computers in the house especially if I had kids oneday. Usually I have my main computer set up in the living room or my room as the entertainment system, depending on where Im living. The normal setup would be desktop, hdtv, and sound system, I'm done paying for cable. I download and watch my tv and movies on the internet and plan to as long as I can. I use an Xbox 360 controller for pc games and emulators and other wireless input devices. I use a free remote desktop connection program I can take control of the main computer from other computers if I need to turn the volume down on the tunes or do tedious maintenance tasks from a more comfortable location.
I have thought about taking it to the next step when I own a house of my own, the main entertainment system could have a wireless HDMI router so I could have another monitor in the kitchen if I wanted to look up recipes or cooking videos. This computer would be controlled by a bluetooth mouse and keyboard. Another advantage is for a PC gamer like me who likes to play certain games on the couch with my 360 controller for windows but some first person shooters I need to sit down at a desk. I only have 1 computer capable of running the games to there potential so I set up a gaming desk somewhere with a keyboard/mouse and smaller monitor. I guess I am kind of split here, I wouldnt mind having the setup above, but I still want multiple systems in the house.
I like the idea of packing all the tech into every device we have like dave said. I like the idea of having multiple systems with there own brains and finding applications to take control each system from another system. Tech is allready leaning that way. That blackbery you gripe about is not a good example. Take a look at some of the super phones on the market. I am currently using a phone with a dual core processor, 1gb of ram, nvidia graphics chip and I can 720p videos on my TV that I load onto my SD card. Newer pones now allready have 1080p playback and recording. The same remote desktop connection I use on windows is also available on android for free.