To me the concern is not whether the USG will ever divest of ICANN, it's whether the rest of the world will come to dislike the arrangement enough to devise a method to circumvent it. By that point, the goal will not be to sever ICANN's tie to the USG so much as to render it either redundant or irrelevant.
That is indeed an interesting question. At this point I'd have to say that the objections to US government oversight are far more theoretical than practical. The only thing they've done in the past decade that's even slightly controversial was to nudge ICANN on .XXX, and I suspect that made them more popular rather than less with most governments. Regards, John Levine, johnl@iecc.com, Primary Perpetrator of "The Internet for Dummies", Information Superhighwayman wanna-be, http://www.johnlevine.com, ex-Mayor "More Wiener schnitzel, please", said Tom, revealingly.