The role of the US Govt is to protect US interests locally and internationally. To hand US sovereignty over to a foreign body that will like make decisions that will hurt the US will be a failure of this responsibility.
You are wasting valuable anxiety on this non-issue. Here are some other things you could worry about instead of ICANN:
Nuclear North Korea, The coming reform and expansion of Obamacare, the structural deficit in Medicare and Social Security, the Islamization of Europe, demographic trends that portend a gigantic wave of low IQ voters over the next 100 years, the incompatibility of fundamentalist Christianity with modern natural scientific understanding and the unwillingness of church leadership to accommodate those incompatibilities.