The event to watch for is the instigation of a criminal case or punative damages case which would bring about a discovery phase in the legal proceeding. THAT will get plenty of betting that it will happen soon, but the natural action will never happen while Obowma is in office because he could not last through the discovery of his forgeries and criminal behaviors.
Or perhaps a criminal case that is accepted by the Supreme Court. Supreme Court justices are human, not totally impartial. If they feel the foundations of the Republic beginning to crumble, will they not act?