I think they would have to replace it with another indoor attraction, to stay on top of things (well try to) considering MW has the Scooby Coaster.
I'd like to see the full knock down the mountain and create a whole brand new experiance, like a mine train ride, starting in a new mountain, similar to the one currently there. The train would zig zag its way thru the 'Mines of Dreamworld' (it could maybe be linked with the Giant Drop theme of the oil digging?) then the train accellerates thru the mountain, coming out at the top of mountain (sorta a Volcano shaped mountain) and the track winding down the sound of the mountain.. The track would then zig zag thru small camel humps around the Gold Rush area, and sorta make a 'border' to the themed area (like the Scenic Railway does at LPM). The track would then makes its way back to the mountain and finish. The main coaster part would consist of no inversions, however it would use a couple of helixes.
I know I'm dreaming big, but we can only dream, can't we? I'd love to see my idea put into a scetch by someone, or whatnot. It would be Superman (accelleration coaster) meets Scooby (indoor coaster for the start, with intensive theming to set the scene) meets Scenic Railway (turns into a proper coaster[metal coaster themed to wooden] for the rest of the track).
Here is my verison of my idea. The blue circle/shape is where the new mountain would go, And the yellow line is the track layout, going anti-clockwise..