Disclaimer - I don't believe he will quit or be fired in the next 4-6 years, and, in fact, I think he will coach as long as he wants.
You and Ryanfield are looking at a situation that is 10 weeks old. As of the day before the season, probably 70-80 FBS programs would have traded coaches with us, perhaps as many as 100, including probably 50%+ of Power 5. I agree the outlook is bleak right at the moment, but the dude was hot property until Labor Day weekend. In fact, probably still a ton of teams with crap coaching would hire him in a heartbeat. Has he hurt his marketability? Sure. Even if he signaled availability, he's not a candidate at LSU, USC, or (eventual) Florida. Heck, I don't think TCU would replace Patterson with an ersatz version.
Fitz is a good coach. He makes mistakes, and then makes mistakes upon mistakes by not taking swift corrective action. But - he ain't going anywhere. I'm older than he is, I think he will be the coach for the rest of my life.