Like others have commented, Apple could release such a device in no time. You can already hook an iPad up to a monitor and keyboard, so Apple just needs to add the OSX desktop. Looking at the Windows 8 reception, I doubt they are going to do that..
What Apple is betting on (and what Microsoft is betting on as well with SkyDrive and unified sign-in) is program data and state being synced seamlessly through the cloud, so that you can have a stand-alone high-performance PC on your desktop (maybe like the iMac).
If Microsoft is indeed betting on "all apps and documents localized on one device", they are betting on the past.
So (conceptually, because iOS doesn't allow keyboard-only navigation), you just tell it to zap on the biggie screen and drop it somewhere nearby, and start typing on the keyboard (hell, merely typing could make it zap to the screen, skipping the first step entirely). No cables, ma.
What Apple is betting on (and what Microsoft is betting on as well with SkyDrive and unified sign-in) is program data and state being synced seamlessly through the cloud, so that you can have a stand-alone high-performance PC on your desktop (maybe like the iMac).
If Microsoft is indeed betting on "all apps and documents localized on one device", they are betting on the past.