What happens to the portions of large glued displays that aren't retasked into a different display? When LEGOLAND dismantles a glued display, is it recycled into something other than LEGO, or do they have to be thrown away?  I know certain portions of a display might be utilized again in a different display, like some cars and trailers from the now defunct Speedway at LEGOLAND California were, but what happens to the rest of the model?
In most cases they would be reused in other parks, donated to LEGO retail stores, auctioned for charity or hidden away from park visitors. As a last resort, LEGO models can and will be recycled to create new bricks. 

The LEGO auction site, Bricklink has a fairly hidden place to trade glued models and retail displays.