Reply #9: A Constitutional Convention would be the easiest.

[PinkTiger]

Some of these changes could take place without one, but in order to change the leadership and the ways leaders are chose, it would be necessary to have a new, amended Constitution that would simply lay out a new way of governing.
The new process would not entirely remove corporate participation or cronyism, but would fragment it a great deal. Influence would not go from region to region without a new organization within that region working toward the goal.
The staggered terms would also take some of the wind out of the sails of those who want to see sweeping changes every 4 to 8 years. We have grown too big for that. And we are too important to the world for polarization with one or two people at the helm.