Before I start, please understand I am not making direct comparisons or analogies here. Only "somewhat similar in effect" observations.
Look at USC and Penn State last year. USC started 1-3, and Clay Helton's seat was made of lava a quarter of a way into the season it seemed. Granted, their three losses were to ranked teams, but the fanbase wanted blood and USC hadn't been shy in firing coaches less than halfway through a season just in the last few years. They ended up winning out and finishing #5 with a Rose Bowl win. Penn State started 2-2, with one of the losses to a really good Michigan team, but this was after two consecutive 7-5 seasons from Franklin. 4 games into the season, the fanbase was pretty convinced this dude was no good. Turned it around and went on an incredible run.
Mike Riley has every chance in the world to save his job, and those sorts of turnarounds have happened before. It wouldn't be the craziest thing ever. The odds are high, but it's totally possible. That said, if he doesn't win the division and lose the conference championship game by less than 10 points or so, or make a major bowl or something, I don't think he survives.