Probably, but not necessarily. My understanding is that the overturning of Chevron means that the courts don’t have to defer to agency expertise anymore, but until EPA’s regulatory power is completely taken away, they can still implement these kinds of rules. Someone would have to bring a case against this particular regulation and argue that harm was caused by it, and that case would have to go through the courts and make it to the Supremes. At that point the Nine Robed High Priests of the Imperious Court could decide that they know better than the experts and then squash the regulation. So it’s not automatically nullified by the overturning of Chevron, but with a bit of work it definitely helps.