Something like Wiimote is definitely the future, but right now there's no way any player with Wiimote/nunchuk controllers could beat a good mouse/keyboard player. A mouse player would be dancing circles around an equally good wiimote player. For me (as a former competitive FPS player) that's the criterion that counts.
For example, try to instantly turn 180 degrees while running, take a shot at an opponent who's chasing you (while continuing to run backwards), and then immediately turn 180 degrees again. Pretty ordinary with mouse/keys, impossible with wiimote/nunchuk.
For the moment, only a mouse can offer accurate reflex moves across 720 degrees.