It (338 Federal) started out with 4 factory offerings. That's more than the 260 Rem, the 358 Win, the 257 Rem Robts, the 250 Sav, the 338 WinMag, and a bunch of others had in the beginning. And the first two mentioned didn't even enjoy four factory loadings in their whole life.
Federal has since added a fifth load. They obviously see enough sales potential to keep working with it.