SHIELD Academy Reborn
SHIELD is pretty much like every other branch of the military, in that most agents receive training at an academy before going out into the field. Up until recently, SHIELD, as an organization, was struggling to be rebuild from the inside out. And one of the directives Mack is working on in his position of Director is rebuilding the SHIELD Academy.
This is first mentioned early on in Agents of Shield season six, when Mack and May recruit Dr. Marcus Benson to fill-in for the predisposed pairing of FitzSimmons. Closing out the series with a few of the main characters, like FitzSimmons and Mack, playing key roles in leadership of the new SHIELD Academy is a wonderful way to keep the story going, and would allow the idea of Agents of Shield to live on past the closing credits.