PE has said that if you can get the color couplers and proper filters, you can process Kodachrome in E6 chemistry with the color couplers added to the color developer. It makes sense to me that you could make a modern Kodachrome with better light fading characteristics by making it with E6 emulsions where the color couplers have been left out. I don't think making the Kodachrome type emulsions is the problem, the problem is the complexity of the processing. E6 film can be processed at home by anyone with a changing bag, a tank and reel, a water bath, a timer or stopwatch, and the proper chemistry. Kodachrome style processing is not so easy to do.