Great discussion, but I don't think anyone has addressed the true question. ddemuth78 isn't asking is it feasible, he's asking if it is even possible. He has already stated the iPad does everything he and his wife do with their computers. The question is, "is it yet physically possible to have an iPad be a single stand alone computer?"
There are two basic uses for a computer, creating content, and consuming content. As a content creator, I find the iPad nearly useless. However, as a content consumer, I find the iPad (or any well designed tablet) to be the best device for consuming. Obviously, if you have multiple monitors or need in depth file management tools, the iPad isnt the right tool for the job. But what if the iPad IS the right tool for every job you want your computer to do? Is it physically possible to have just an iPad without another "real" computer to connect it to? Someone else already mentioned, by adding a simple case with integrated keyboard you have resolved the main issue with any content creation, the virtual keyboard reduces everyone to "hunt and peck" mode. Alternatively, you could connect a Bluetooth wireless full keyboard as well so you can type on your lap. First issue resolved.
The biggest issue I see with having the iPad as your only computer is that it simply wasn't designed to be so. It was designed to be managed by syncing it to the main computer using a USB cable and iTunes as the management software. However, the reason the main question can even be asked is because eventually, once you've got the iPad set up the way you want it, and you've transferred your music (which largely lives on iCloud now for free with the advent of iTunes Match), and photos from the main computer (especially if you now use the iPad as your camera so no more transferring required), once you get to this point, you really don't need to connect to you computer any more. Or do you?
For the email, music, pictures, games, and video chat crowd, once you've got the iPad set up the way you want it, do you ever NEED to connect it to a computer again? THATS the question. Plus, is the question (or the answer) different for the owners of different generations of iPads (or other tablets).
My mother plays games, does email, browses, takes pics on a camera (iPad 0, no camera) and uploads them to various sites. Her Wintel machine is 15 YEARS OLD!!!!! She is an artistic person and hates the machine and all the boxes and wires.she loves the wireless iPad. Clearly, if she is going to continue to own a computer it's time to get a new one. It would be a MUCH more pleasant experience on a new computer, but she will still need to got to the computer to use it, and still have to look at the modem, router, and accompanying wires. Question, can she use the iPad wirelessly in the living room, using the HD flat screen TV as the monitor, the virtual keyboard or Bluetooth keyboard and the iPads touch screen for the mouse and NOT buy a new computer? The question isn't "is this the right thing for her?" It absolutely is. The question is, can the iPod successfully survive without being synced to a main computer ever again?"
The only reason this is even a question is because the iPad was never designed to do this. It may have been envisioned as being able to do this one day, that may well be its ultimate function, but as yet, it has not been designed to survive without the occasional syncing to a main computer. Keeping in mind the iPad is really just an iPhone without the phone. Even iPhone, until the current release of iPhone 5 was meant to sync to a computer. My understanding is that the new 5 can in fact live successfully without syncing to a computer - the market wanted it so Apple delivered. So, can the iPad currently do the same or is there still a generation or two to go before it gets there? Especially the iPad 0. Are there things that it simply needs to be synced to the computer for that would hamper its function as a stand alone device? I don't know. What I do know is that it was designed as a side car, as a piggyback unit, as an extension of your main computer to give you a consumption option other than sitting at that desk in that folded up shape.
My mother is asking, and I am investigating. It seems like it should be able to survive to on its own, without another computer, but it wasn't designed for that so I am loathe to tell her yet that it is OK.
Anyone got any absolute knowledge one way or another, or resources that can be used to get a definitive answer?
Thanks.