I suspect the reason Smith stopped .357SIG was the same reason any manufacturer stops production of anything, lack of demand. I realize there are many fans of the cartridge (and I think it's interesting kinda like the .30 Luger, another bottleneck pistol cartridge) but in the end, accountants and shareholders make the decisions. They look at the numbers and if it's not selling as well as other models, and they need the production line to make something that sells better, it gets the axe. I suspect the .357 SIG line was converted to Shield production. Just my take on it. Remember the .41 Magnum? Can't remember the last time I saw ammo for that on a shelf.

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