Best Case Scenario
Mike Franks was not one of the team in a technical sense, but to them he embodied hope. He was the cowboy, the rogue former agent that could stand up to any situation and walk away with nothing to show for it but his daily increase in smoke inhalation from a string of casual cigarettes, save one severed digit. He was tangible proof that they could, just possibly, survive this profession more or less in tact with their wits about them. Gibbs had his superior senses and his impervious gut, but to them Mike possessed agent immortality.
They were mourning the man, concerned for their overwhelmed yet undemonstrative boss, but the group hug they shared was to comfort each other in their own insecurities. If Mike could succumb to something as common as a bullet on an ordinary rainy night, that meant all bets were off. Somehow this was more disturbing than the thought of being captured in a terrorist camp halfway around the world, fighting off medieval diseases, or chasing drug cartels.
They melded into one mass of anxiety and despair. They held each other because they could no longer be ignorant of each person's fragility despite training, instinct and acute awareness. If Gibbs could lose Franks, who's to say that tomorrow it won't be their sensibly gifted McGee, or their hyper vigilant Ziva? And what would happen if Gibbs jumped ship over this and they lose his cohesive leadership before the head slaps even have a chance to return?
They couldn't voice those fears, and so they clung, they savored each other while they could because it is very likely that one day Gibbs will retire out of spite, one of them will be shot, another will get transferred, one will have a nervous breakdown, and the last one standing will buy a house with a basement and will bide his time. And that may be the best-case scenario.