I know this, what's your point? What if the EPA drops regulation of lead in garden hoses, Congress introduces a bill that says "states cannot have more stringent regulations for lead in garden hoses than the EPA", the president signs it, and the legal challenge to it reaches the Supreme Court where it's defeated 5-4? You take it for granted that states have certain rights historically, and that the current government will respect established norms and rules (and failing that, the institutions of government that should protect against this will not fail). My point is you should not take that for granted any more.
My point is exactly that, that states do have a right to self-regulate, notwithstanding constitutional questions.
The end-position that you describe would be terrible, but it's very possible. But I don't think the states would go down without a fight, and I don't think the Supreme Court should ever be looked at as a slam-dunk; many Presidents have learned that lesson.
It would be a very awkward argument that the Feds know garden hoses best, at the same time that the Feds are saying that States know health care best. And courts so far have shown themselves willing to consider what this administration has said in recent history about the Muslim/Travel ban to judge intent and constitutionality. So the two self-contradicting points of view ("We know best," "they know best") are likely to get some scrutiny.
Just because things look dark doesn't mean it's over. Even if you're a cynic.
