The patent is still active. Considering how many "large" MTL-compatible couplers are currently in use, maybe there is a chance that someone or some company could pick this up. I don't see the entire Anerican model RR industry switching to Andrew's couplers anytime soon. If Andrew found a way to manufacture those delicate miniature springs for his coupler, there must be a company out there which could produce the simple pigtail type whisker spring needed for Protomates.
