I worked for a company whose factory really was just a room - the company was a machine-builder, a B2B manufacturer of custom production equipment, but with very little investment in special-purpose machinery for its facilities or even machine tools, just an attitude that the company is the people and we can do or buy anything that our customers need.
In some ways that attitude seemed admirable, but ultimately it didn't help the company win or keep consistent business. You'd have gaggles of smart people building custom prototypes but nothing scaled up. The customers couldn't see the vision of scaling their production there, or just saw that they could get better pricing going to factory which had already invested in the right special-purpose machinery.
That's what a factory is to me - ideally reconfigurable, but a place with capital investment for production. It's good to show kids what's behind the curtain but don't get it mixed up with a prototype shop.
Factories, were like that. Giant Mills, Planing machines, vacuum forming tooling, welding stations, etc. Configurable, yes. Tooling, yes. It's why ford, singer and a hundred other american factories could start making bombs, guns and anything during WW2. You had machinists who could read a drafting diagram, and drafters who could draft anything up.
Today, could we do that? probably not. Not even - we don't have the basic bootstrapping tools in capacities needed, we don't have a wide group of people with the skillset.
So yes, you can make anything in a factory designed to make mostly anything
With specialization, especially like in the auto industry, you'll have one shop in mexico that gets an order 6 weeks ahead of time and has to deliver down to the day on the production schedule of ford to supply say a car headrest, and thats it. So, could we... today... maybe?