I am not judging anything based on what has happened in the 5 months leading up to this, right down to the hubs.
Keeping in shape has to be on the players, not the coach. He was not there to run practice. We have no idea of who tried to stay in shape and who did not.
Yes, it was an embarrassment and the blame goes all around. The roster, as currently constituted, is still a bubble team. Bubble teams can miss the playoffs just as much as make them. This was still the youngest team in the league. This was still a team that completely overachieved over the course of the year. Making the team harder to play against, has to do with personnel choices. That is up to Gorton & JD, not Quinn.
As there is not as much as one whit to point to a belief that Gorton & JD have soured on Quinn, I will maintain that short of the wheels completely coming off the bus and the younger players regressing, there is absolutely nothing to indicate that Quinn would be fired. There is a world of difference between competing for the playoffs all year and falling short, and competing for the lottery.