Not all manufacturing plants are designed to be modular. Modularity of components can only go so far, then human intervention becomes inevitable. Having a robot open an enclosure to replace a input/output module of a PLC, let alone re-wire it is more complex than plug and play. Also to that end, how does a robot modify electrical/mechanical prints? By what protocols? A better construct would be a human - machine symbiosis. Once again, good luck with that.