Recently, a few brands (Wooting, Razer, Steelseries, etc) have introduced keyboards with analogue-capable input (using either hall-effect, like the switch in th

Recently, a few brands (Wooting, Razer, Steelseries, etc) have introduced keyboards with analogue-capable input (using either hall-effect, like the switch in the article, or optical sensors). This already allows the actuation to be set per-key in software, so your idea probably wouldn't even be that hard to implement with today's hardware! (although you may need a beefier microcontroller on the board)