That said, the Supreme Court also had language suggesting that one reason it decided in favor of South Dakota was that its requirements weren't onerous. This might suggest, for example, that states should have some minimum threshold but the decision didn't supply one or state so explicitly.

IANAL but, if I head to guess, this isn't going t be an apocalypse but there are going to be some uncertain times, some state will probably push the boundaries, compliance costs will rise, many small businesses won't comply and try to fly under the radar especially given it's not clear what teeth a state has against out-of-state retailers with no physical presence, etc.