Moving it to Pittodrie makes little sense to me, they'd need to pay for the use of it, and lets face it, a midweek trip to Pittodrie would attract what, 150 well fans? max?
Take a lot of local interest away from the tie and Loco's are going to be out of pocket, maybe a gate of 1,000.
If it has to be switched, I think the only logical move would be to hold it at Fir Park, giving Loco's free hire of the ground and guaranteeing a gate of around 4,000.