Apple got rid of the "box under the desk with expansion slots" in 1984. To be fair, they started the "problem" in the first place, however. Prior to the Apple II, PC's were "all-in-one" boxes with no expansion slots. (Obviously, I'm discounting the entire S-100 class of machines such as the Altair, Imsai, etc., as they weren't really mass-market devices.) These days, every major manufacturer has dozens of computers that only require one cable for power. The ones without batteries are called "all-in-ones." The ones with batteries go by the terms laptop, netbook, tablet, etc.
One board "all the way? I carry that in a pouch on my belt. Some folks keep theirs in a magazine-sized sleeve. Actually, I'm typing this on one right now. It's balanced on my left knee as I sit on the couch drinking rum & coke with "Mad Men" paused on the TV (which is being fed from a game console that is connected without wires to the computer that the actual video file is stored on.)
Cables running to external devices? Already history. The only cable running to the machine I'm typing this on is carrying power, and I can unplug that for 5-6 hours at a time. On the floor next to me is a keyboard about 5" wide, and a tiny mouse as well. Neither of them have cables. There's no cable connecting me to the internet. Heck, even my printer only has one cable, and again, that's carrying power. The only thing I still "need" a cable for on my "big" computer is the video display, and I expect Apple will invent a proprietary reason for that to go away within the next few years.
I'm not trying to be a dick here. I'm just saying that if you actually step back and look at the history of computing over the past 30-40 years, it's really kind of amazing how little has changed in light of how much has changed.
The way we use computers today just absolutely blows my mind, and I'm sure that part of the equation is going to continue to evolve in ways I can't even imagine. But the way computers actually work hasn't changed one bit since the Beatles played on the Ed Sullivan Show.
The way we will use them is as much what I was talking about as how they will work. I was referring to desktops with no wiring, in a much more compact package, much like the ASUS EeeBox thing. Make a desktop built much like a cell phone, and with standard wireless keyboard and mouse, as well as the future of wireless external storage, and the way the wireless devices synch flawlessly without the hassle of configuration and finding working drivers. Instant synch between cell phone and desktop allowing for easy, intuitive transfer of data, again without setting anything up. I guess you could call it ease of use. Or even do away with the desktop machine, have a cell phone powerful enough to simply work as the muscle for a home setup, monitor, speakers, keyboard and mouse, all wirelessly, all with instant connection with proximity of the cell device.
I understand what you are saying thought, about not much changing. In some ways it's very similar to back in the day, but at the same time, things are so very different in pure computing power, what we can do with it, and how we use it day to day. I can just remember feeling on top of the world in 95 playing Flight Simulator, the thought that I would be able to play games 10 times as big and graphically intensive on a portable device that fits in my pocket, only 15 years down the road would have blown my mind. Just as technology 15 years from now will probably blow my mind. At least in a giddy, kid at Christmas kind of way.
Wow. Forgot how many hours I spent playing that game. My friend and I both picked up the "Gold Edition" and then would play head to head by dialing directly into each other's computer. Seemed so revolutionary to actually be playing a computer game against someone all the way on the other side of town.