I think this disabled, immobilized or destroyed permanent wreck system combined with Company of Heroes cover system could make the wreck of a defeated tank column into the covered approach of an infantry platoon. could be a lot of fun. Lighter vehicles could act like red barrels, being an explosive target for someone fighting someone foolish enough to use it as cover.
To save on data the library of instanced map objects could have a dynamic portion that allows dead units to be added and subtracted (if destroyed or salvaged) from it making the rules of the map's instanced objects apply to it. Maybe create a texture set that can be carried over to any wreck and corpse, the dead unit could then be replaced with the identical instanced map object and the instanced texture data, making the dynamic object into a static part of the map and level design.
This could be especially impressive with huge ships in low orbit crashing into the surface. Becoming a whole new part of the map and dynamic addition to the game since every time it crashed it would be different.