Actually, I was just thinking that right before I read your post. Remember, this is an facial challenge, and not an as-applied challenge. IOW, plaintiffs aren't (necessarily) arguing that the enforcement of this is wrong, but that the statute is wrong, in and of itself.
I don't know why the state couldn't create some other kind of public policy narrative - like an EO, for example - that directs the same exact kind of enforcement. In fact, I think they probably could. It's the codification that has largely gotten them into trouble, at least in this court's opinion.
Now, I'm sure that down the road, that would be challenged as-applied, but from reading this particular opinion, I'm not convinced such a case would prevail.
I believe such an action would place the governor in the position of making foreign policy, and thereby trespassing on the Constitutional authority and jurisdiction of the president to do so.
Noonan's opinion deals with a similar issue (a state in conflict with the president's power to conduct foreign policy), and I feel certain that an executive order of the sort proposed, would be squashed on that basis.
As I understand it, one of the reasons AZ passed this law was to make sure it's "sanctuary" cities were actually enforcing existing law, and weren't looking the other way when they came across illegals. That, because of this opinion, will probably continue to be an issue.
The Court is saying that it's not possible for states to create any kind of law regarding immigration, and I would take that to be inclusive of statutory and administrative law as well.
AZ, and other states, are going to continue to struggle to manage or correct the actions of these certain municipal districts that give a kind of safe-harbor to illegals, if this opinion carries the day.