As I see it, the 358 win will not do anything the 308 cannot handle.
Quite true, but not very relevant as all the medium bore cartridges hunt the same class of animal quite well. The ancient 9x57 was well regarded as a hunting round, now almost forgotten after the introduction of the 9.3x62 and 375 H&H.
Being a good hunting round doesn't guarantee market success, but market success doesn't mean something is a good hunting round (the 223 Rem for example, excellent cartridge for what it is but not something I'd choose to carry for elk).
Jimro