In a "normal" situation, the President would step in for the CEO. In this specific situation, I would expect the CFO to step in as the interim President given that he previously held that position for ~6 months while they searched for NP's replacement. Also, the COB isn't an employee or full-time position, and they're not going to oversee day-to-day operations like the CFO. They're frequently employed somewhere else and are only in an advisory role.