I agree he is probably signed, sealed and delivered to the Chooks, but...Gus saying he won't be at the Dogs is nothing to hang your hat on. He has form with this sort of thing. I recall something along the lines of 'Trent Barrett will be coaching the Bulldogs long after I have left' before sacking him a couple of weeks later.
Gus just doesn't want to be part of the media conjecture for fear it will distract his players, i.e. Toby Sexton, etc. It's not beyond the realms of possibility that Gus signs DCE and spins a yard about circumstances changing and an opportunity arising....blah, blah, blah. He is a spin doctor and not the least bit concerned with credibility when it comes to the ruthless pursuit of excellence.