Yesterday I participated in an NTA panel that addressed U.S. international tax policy and where it should be heading. Others on the panel were Jane Gravelle, Ed Kleinbard, and Lee Sheppard, and Jim Hines unofficially served as commentator via extended questions that he asked each of us, as a kind of point of personal privilege (quite reasonable, I thought, under the circumstances) because the panel tended to disagree with him.
All 4 panelists called for improving the source rules so the U.S. can more effectively tax multinationals on the fruits of their economic activity in the U.S. Kleinbard and Sheppard argued that we need to retain and strengthen worldwide taxation, essentially as an indirect way of taxing U.S. multinationals on their U.S. income. Gravelle views the U.S. as having sufficient monopoly power to be able to benefit from imposing a very aggressive tax on worldwide income. I gave the very quick version of my current views, under which switching to exemption is fine if we (a) really improve the source rules, in particular by treating all worldwide multinational groups as a single company, (b) tax the transition gain from U.S. companies' existing $1 trillion pool of overseas earnings, and (c) quite reasonably assume that exempting foreign source income is the only way to get rid of foreign tax credits and deferral.
The slides of my talk are available here.