This opens the possibility to get Factorio to 3D!
All you need to add is ground slope up and a ground slope down (working like your ladders) now generate terrain ... the normal level can have either ravines / holes with sometimes slopes into them, or it can have hills / mountains that (inverse mechanic of ravines) and tada 3D Landscape.
Also add flying mobs ... to balance the ability to make flying factories.

The game is designed to be 2D, and everything is based of that. To "upgrade" to 3D would require an entire rewrite of, well, everything.

This mod just adds more 2D planes to work with.

This mod basically makes a crude form of Dwarf Fortress with factories. Something i WHoleheartedly cheer for.