We are in the era of the sub compact handgun. Most of them in 9mm, probably the most cartridge anybody wants in a subcompact. I shoot the .357 Sig in a P239, a compact, and it's pretty much at the practical limit. Glocks are probably chambered in this caliber more often, and they aren't small either.
Maybe you can put 5 lbs of stuff in a 1 lb bag, but that doesn't mean you can sell it, or make it shootable, or find people willing to touch it off. When larger pistols return to vogue, so will the .357Sig.