From my understanding, the San Bernadino phone has already been unlocked. The feds want the ability to unlock any phone without having to ask Apple. Sure, they will get a warrant first...SURE!
I say they get a warrant and apple unlock it for them on a warrant by warrant basis.
Others say they are waiting on hundreds of phones to be unlocked already and they want to speed the process up. If that is the case, then pass legislation that says, barring a court order, phone carriers have a limited amount of time to unlock the phones until heavy fines set in.
But do not give up the codes.