I've had this in mind ever since I built my first layout that was bigger than a 4'X8". I figured I still had a few moves to do in my lifetime so I built my subsequent layouts with moving them eventually in mind. The move into our current house was exciting since the basement was much larger and I'd be building my biggest layout. So I kind of looked forward to packing everything up.
I built my benchwork, including my current layout, in module style so it could disassemble easier. I framed each 4X8 piece of plywood separately (I wish I made them 4'X4', more modules but lighter to move) and attached them together with 3" drywall screws.
When we did our last move, after packing the trains and scenery away in storage boxes, I just backed out the screws holding the modules together then removed the legs for each module and stacked up the framed benchwork on their sides for moving. I stored the detached legs in separate tall boxes from a storage store. All the boxes or plastic totes were numbered and I made a short list of their contents. I put the box numbers all over the box so the movers would know I had them inventoried. Since we moved within driving distance from our previous home, larger and/or expensive locomotives were transported in my car for safety.
Once I began to rebuild in the new house it was fairly easy to just reattach the legs and place the modules in place. However, I needed a lot more lumber to fill the new larger basement. The mistake I made was buying it all at once. While setting up the rest of the house, the lumber began to warp in the humid basement. I was able to salvage most of the framing lumber by just putting together the warped pieces as if they were straight which resulted in some twisted framing. Once attached to the wall I placed heavy objects on it and eventually it straightened out sufficiently. So only buy fresh lumber for what you can build in a short time.
What you save from your layout will depend on how you constructed it. All trains, track, trees, buildings and any landscaping I could remove were saved. Mountains and their framework were demolished and trashed.
I figure I may have one more move left in me someday, hopefully for a bigger layout, so the layout will be ready to remove when the time comes. By then if I need any additional lumber, I will probably go with Mianne Benchwork to make it easier.