The fed did nothing.
So AZ tried to defend itself against the onslaught, tried to take care of itself when those who were supposed to be doing that job refused, and they tried to call attention to their plight.
Well, that last part worked .. and to the degree that the most controversial part of the AZ law was upheld.
I'm pretty sure AZ never expected the SCOTUS to let them arrest and deport etc., the federal government's constitutional job.
But it would not surprise me if the detain and question and report to the fed part that was upheld -- historically a part of inter-agency law enforcement cooperation -- was the real objective all along, the validation that inter-agency reporting as a threat to illegals is alive and well and that the state and its local affiliates do have communication power to find and report illegals so that the fed has a record of who to pursue, and that the SCOTUS's constitutional concurrence of that make it clear that such efforts of AZ state and local law enforcement personnel could not be "overriden" or "ignored" by some federal wing-nut in pandering power at the moment.
Smart, really, all things considered.