This is a great idea and could be relevant in many different contexts. For example if one was building a layout, but thought it might be torn down in a few years to move. Modules could be moved from one layout/house to another. Also, modules could be used on floor layouts, and as mentioned swapped in and out of modular layouts.
I made some small ones years ago and made a mistake in not making the module bases robust enough.
There is probably a need to standardize sizes and mounting systems. What have you done about that?
Bill