This is speculation, but it’s based on a statement John Bolton made about two hours ago: In Austin, John Bolton voices support for officials called in impeachment hearing (KXAN Austin):
Speaking at a private event in Austin Thursday, Former National Security Advisor John Bolton defended government officials who testified in front of the U.S. House impeachment inquiry.
. . . .
Sources tell KXAN Bolton defended former diplomatic and state department officials Fiona Hill, Tim Morrison, Alex Vindman, Bill Taylor, and Marie Yovanovitch.
“All of them acted in the best interest of the country as they saw it and consistent to what they thought our policies were,” said Bolton, during the question-and-answer time after his keynote speech.
He went on to say members of the Trump Administration should “feel they’re able to speak their minds without retribution.”
This sure sounds to me like a signal Bolton is going to make sure he’s heard one way or another.
There is genuine concern that Trump may be able to suppress the book (dKos diary We May Never See John Bolton’s Book is just up, based on a NYT op-ed of the same title). But prior restraint is not allowed for speaking out (maybe some rare exceptions, but I bet Bolton, a savvy lawyer, knows how to get around that).
I read Bolton this way: He clearly sees no future in a Trump-only Republican party, he clearly despises Trump (for some of the same reasons we do, and also for some different ones), and he sees his best chance to look good in the history books is to tell what he knows now. Somehow.
I would not be surprised to learn there has already been an interview taped and ready to be released.