That should be achievable by adding another screen on top of the one on this machine, hinged at the top. In closed position the thing could work as a tablet, in

That should be achievable by adding another screen on top of the one on this machine, hinged at the top. In closed position the thing could work as a tablet, in open position the top screen would flip 180° to form the top part of a large 4:3 screen. The main body could be set on rails, to slide forwards from under the keyboard when the thing is used as a laptop (more or less the inverse of what slider phones did, here the keyboard stays in place while the body slides away from under it). Add a touchpad to the main body and you'd have a relatively normal laptop configuration.