Don't forget, the King Cobra wasn't based on the more complicated, V-spring lockwork of models like the Python, Detective Special, Diamondback, etc, etc. The King Cobra was an AA frame gun based on the MkV/MkIII guns that were introduced in the late 60's specifically intended to be less expensive to produce than the V-spring lockwork was. A new age King Cobra shouldn't be any more expensive to produce than a L frame Smith and Wesson assuming all else is equal.
If Colt had smart management and the coin to do so they would be well advised to reintroduce the Magnum Carry/DSII, King Cobra, and Anaconda revolvers to cover the small, medium, and large frame revolver markets....although I would suggest giving the small frame revolvers snake names for marketing purposes this time around. Then, if they were so inclined, the could reintroduce the Python as a custom shop only piece and have all the bases covered at a time when the market is very conducive to making big money on guns.