I find it highly unlikely that mom-and-pop stores will have to collect and remit taxes to other states. From they very start of Quill they said: "we ruled that

I find it highly unlikely that mom-and-pop stores will have to collect and remit taxes to other states. From they very start of Quill they said: "we ruled that a "seller whose only connection ... is by common carrier ... lacked the requisite minimum contacts with the State." So the issue was: how substantial does the seller's contact have to be? The court ends this decision by saying "the first prong ... asks whether the tax applies to an activity with a substantial nexus with the taxing State... sellers who engage in a significant quantity ... are large, national companies ... undoubtedly maintain an extensive virtual presence." So the issue remains: how substantial does the seller's contact have to be? The underlying logic of the law hasn't changed, they just fixed some imprudently broad language referring to a physical presence. So I doubt the SCOTUS abandoned one bright-line rule for being flawed in favor of another bright-line rule that equally fails to address the underlying issue of substantiality (e.g. imposing a "single-sale" rule).