I may be the lone wolf, but I think this book tour is the start of his conquest to become the next Secretary General of the UN. Its the only way he retain any sort of power that will disrupt and maim the lives of his fellow human beings.
He still has time to be elected President again.
But that's unconstitutional! you say. Well, you're right about that. But here's what I'm thinking.
Many Republicans want a constitutional amendment to allow Arnold Schwarzenegger (or any other naturalized US citizen who has been here a very long time) to be eligible to be president. Democrats, knowing what that's about, will never support that.
Many Democrats want the two-term limit for the presidency lifted. (Really. Go back and look while Clinton was president and see how many times that proposal was made in Congress.) No Republican is likely to support that.
Combine the two, and you've got an amendment that might just pass, and Bill will certainly get behind it.