If you look at the average age of the 6850, not mention the 140M, it's hard to justify the R&D money to develope a retrofit. Most owners of such equipment will opt for a full Mod. The customer needs to ask themselves: If I spend say 20 grand on a selector upgrade, the rest of my elevator is 40+ years old, why not spring for the complete package. If I fix the selector, what other obsolete devices will fail?