I agree. I don't even think 1-11 would get him fired, though I do think there is potential that if you have a bad enough season, they put pressure on him to make changes with assistants, particularly McCorvey if the offense doesn't improve.
Coming off a winning season, he's bought himself an extra year past this one unless there are some off the field issues that push him out. Simply losing wouldn't be enough.
Granted, I could see a scenario similar to Cutcliffe if you were to go 3-9 or something along those lines. I think if you were to go 3-9 or worse, maybe even 4-8, Byrne may put pressure on him to find a new OC or make some other changes. Knowing Croom and his loyalty, I think there would be a good chance that he'd refuse, like Cutcliffe did, and if that happened, it would just be a matter of whether or not Byrne would actually pull the trigger, or whether he'd back off and let him have another year regardless. To me, that's the only way outside of off field incidents, that he would get pushed out after this fall.
I still think your team rebounds enough to get 5, maybe 6 wins though, which would make the discussion a moot ("mute" for the idiots) point.