I think you have an unnecessarily dramatic picture of what this looks like. The AIs dont have to be a unified agent or use logical decision theory. The AIs will just compete with other at the same time as they wrest control of our resources/institutions from us, in the same sense that Spain can go and conquer the New World at the same time as it's squabbling with England. If legacy laws are getting in the way of that then they will either exploit us within the bounds of existing law or convince us to change it.