I think tablets will replace "PC's". But I think it won't be as bad as you think, You'll still have you dev environment, you mouse, keyboard, and touchpad all working in harmony. Here's a snippet from another post I made (discussing mobile vs desktop OS's, hope it provides some alternative viewpoint:
"I'm pretty sure this is the direction all OS's we will be using are going to end up in the coming years. Some people will cry and yell and holler that there is no way something can be made for both keyboard, mouse, and touch screen. I see this as simply a failure of vision. That's absolutely the way things are going to be going, and it's coming sooner rather than later. (I actually think the OSX launchpad is pretty close to allowing this implementation) Devices are getting smaller and smaller. I use a Mackbook air. but guess how it gets hooked up at home? That's right, wireless keyboard and mouse, nice big monitor, I never see the actual computer. It's only a matter of time before my laptop gets replaced by a tablet that has comparable hardware specs. The OS allow for my normal desktop interfaces, along with a nice touch screen interface. I'll use it to pick out movies to play on my TV, from my couch. I"ll use the same device to write code at my desk (with big monitor and keyboard). My kids will use it to play video games, both mobile, and on the TV. I'll use it to send email in the backseat of a car moving at 65mph. (As a wireless comms guy, I fully appreciate the technology it takes to perform that last action.)
But the bottom line is, It's going to happen. Sooner rather than later."
I guess my point is, mobile and desktop can blend perfectly. Those that don't need a monitor or keyboard won't get one, devs and graphics guys will. Technology will keep the size of processing power shrinking. Could you ever imagine something as small as an MBA being a full on computer.
Last bit, and my only reservation of this whole "movement", is that, I hope they keep it more open, more like OSX, vs overly walled garden a-la IOS. But the signs are there, I think it can be done, and done very well, it's only a matter of time.
edit: It seems you biggest problem address the issue that these devices are built for consumption rather than creation. And I'll agree, that's my biggest reservation about the mobile concept. I guess I could have been more clear about that. I'd like my iPad (not that I actually have one) to be more like OSX, where I can hook up a monitor and keyboard, and go to town on my OS. While being able to switch into the "launch pad" mode while mobile.