Pardon me for manipulating your words like a politician would...
The reason for the decline is that there isn't much of a demand for a short range thumper like the Federal. If there were the .358 Win would be immensely more popular on the commercial rifle market as well. Believe me the .338 Federal is here to stay and the reloaders and rifle loonies will keep it going.
So, the Amercan hunter would not be best suited with short light rifle in a caliber that will take deer/antelope/elk at 0-300 yards?
It is my experience that the American hunter wants to live the dream that the need a 300 Wallhanger that will have 0-600 yd straight line trajectory and enough killing power to drop whatever, even if the hit it in the ear. It would be best if it requires no practice, weighs 3lbs with a 2-29x72 scope and shoots $8.99/20 ammo.
^^^That is why the 338 Federal failed. It can't make the false promises that the 270 WSM and 300 Rem Ultra Mag do. ... Or at least the experts at every LGS tell me so.