Some of the current generation of sims (FSX, DCS) focus on "clickable cockpits" where you can operate basically the entire thing via a HOTAS and your mouse, flipping switches and turning knobs. While playing DCS I actually rarely touch the keyboard and move it completely out of the way.
The current head tracking solutions like TrackIR actually make it pretty hard to flip switches on the sides of the cockpit because they drastically exaggerate your head movements.
So I could see Oculus Rift working pretty okay for these. For the ones where I'd still need a keyboard, I could probably hit the right key most of the time without looking, or so I'd like to think.