I think that the SMG should be replaced by an Assault Rifle. It already behaves like one, and it should be a simple change. Think with me: The SMG is intended to be a close-quarters gun, and what it does right now is a medium-range multi-purpose gun. It can take targets from long to close-range, being best used at medium range. But a SMG is intended for close range. The problem is: If we get a close-range shotgun AND a close-range SMG, then there are two guns occupying the same territory, with a gap at medium range. The obvious option, since the SMG was introduced, really, would be to use an Assault Rifle with the stats we have nowadays, slightly nerfed, to occupy medium-range.
TL;DR: Replace name and skin of the SMG with the one of an Assault Rifle(IMO,M16), that makes more sense as a medium-range weapon.
Also, gtfo with that "just mod it" bullshit. I do it already, and includingly use a FAMAS skin for SMG.