I believe the real problem is that the generation of buyers that are interested in the Colt Python are dwindling in numbers every day. I think of it similar to retro-cars. Those that remember fond outings in a 57 Chevy aren't a large of enough group with enough money to get GM to make a modern 57.
I think that modern machining processes can reduce the amount of hand fitting necessary to make a modern Python. So I don't think it is cost prohibitive.
I also think that if one was made it would be similar to how people respond to the Walther PPK. There are those that say, "I wouldn't own the S&W PPK, the beaver tail is wrong, ..., its not the real thing." People would look at the new Python and say, "Oh, that's the new Python. It will never be worth as much as the original."
So, for those that talk like they want the highest quality firearm made, what do they have in the safe? I imagine there are plenty of hand build firearms made somewhere today. My point is, I think most people like myself pine and dream about these things but our actions prove we won't spend the money.