In particular, this is the clarification that I was pretty sure was the case but couldn't find a lawyer who'd said so yet:
> None of this means that Congress cannot delegate certain matters to agencies. Indeed, Loper says that Congress can still provide agencies with discretionary authority. But Congress must do so through statutory provisions or language where the best reading of the statute, applying traditional tools of statutory interpretation, is that Congress delegated discretionary authority to the agency, subject to ordinary constitutional constraints. Silence or ambiguity alone no longer requires a court to conclude that Congress delegated authority to an agency.
So many comments on the day of insisted that this meant that Congress would from now on have to spell out every detail of every rule, and if they didn't do that then the district courts would create a hodgepodge of contradictory interpretations that would make interstate commerce impossible.
Yes, there will likely be statutes that need to be rewritten (though, as noted in TFA, not as many as people feared). But they'll need to be rewritten to expressly delegate the authority, not to spell out every rule.