If Gen. Kelly's departure as CoS to POTUS is 100% confirmed by POTUS as 'Real' news:
Then Dec 8, 2018 has (2) = Major Markers.
General John Kelly (CoS) - USMC → Replaced at 'End of Year'.
General Joseph Dunford (Chairman Joint Chiefs) - USMC → Replaced by Army Gen. Mark Milley
Considering 'The Plan' as a Military type Op. → This is a Major Change in command structure.
Significance to be evaluated.
Marker for 'Next Act / Phase' of 'The Plan'?