Barring a miracle, John Fox is as good as gone. The Bears would need to win out and make the playoffs for Fox to keep his job, but that is impossible at this point. The question at this point is not if he is gone, instead, when will he be gone? The safe assumption is that Fox will remain the coach for the remainder of the regular season before the Bears let go of, however, a midseason firing could still always happen.
It is very tough to see a midseason firing because of all of the cons, the biggest reason a mid-season would be a bad idea is that the Bears are a very young team. Since Chicago is a very young team, it would be a problem to have a coaching change in the middle of the season. Right now the Bears need to move away from wins and losses and move on to developing Mitchell Trubisky, Jordan Howard, and the rest of the young players. At this point, it is probably too late for an interim coach to make as much of an impact than Fox can right now.
There would, however, be some positives to firing Fox now. The first one that comes to mind is that a coordinated steps up as the interim coach and shows a lot of potential as a head coach. It could also be a change of style for some of the young player, however, that could be either a positive or negative.
I think that Fox has no chance of returning next season but I also think that it is almost as unlikely for Fox to be fired before black Monday.