Well..... At least you won't lose the key, right?
You said that the lock cylinder goes back into the position that you should be able to remove the key, by that I can only assume that you mean the OFF position and not the ACC position or the slight in between that some cars have. That indicates to me that the park signal switch is not the culprit since those usually prevent the key from being rotated all the way to off (although I have no experience with the A6 so it might not work quite the same way).
Does the key wiggle at all but just own't come out, or is it seized and won't move at all even slighty up an down? My advice would be to try and find out how the cylinder itself comes out as you may have some small debris blocking one or more of the pins.