The two policy options available to us are 1) regime change through invasion or 2) disarmament by inspections backed by force. If Saddam were to be assassinated this afternoon, no additional options would be presented. The core of the justification for any intervention in Iraq is that Iraq poses a substantial threat to American interests. The core of that threat is the existence of weapons of mass destruction and the potential for development of additional WMD including a nuclear arsenal. The substitution of a different Iraqi strongman for Saddam in no way changes that threat.
...We should not base a policy of disarmament on the good intentions or cooperation of the Iraqi government. Disarmament must be carried out by international inspectors and backed by credible force. If it dependent on the cooperation of the Iraqi regime, then it is the wrong policy option. Our idea of an inspection policy backed by force does not require Iraqi cooperation. If the Iraqi government impedes the inspectors, then force must be applied to accomplish the disarmament.
...The major issue with regard to a policy of disarmament through inspections backed by force is whether or not they will work. If you believe that such inspections will work with Saddam in power, there is no reason to think that they will not work if Saddam is deposed. If you believe that inspections will not work with Saddam in power, it is difficult to see why that position would change when another strongman takes his place.
One of the posts in the comment thread also notes the contradiction inherent in the Administration's predictions that the Iraqi military would stage a coup to avoid casualties, but would launch a weapons of mass destruction attack in which the Iraqi armed forces would incur much greater retaliatory damage.