Important to note that the new National Security Advisor is the same guy President Trump sent to Sweden to arrange the release of rapper A$AP Rocky on the theory that he was “hostage” as opposed to someone who had just been arrested for a crime.
More seriously, it is probably best to see this appointment as the analog to Stephanie Grisham as Communications Director and Press Secretary. After a lot of chaos and firings, Trump works his way to a non-entity who will simply allow him to do the job himself.