Eh..... Friends don't let friends drink the Bayless. That's a Skip rumor and it's never really been verified by anyone else. And it wasn't another HC, it was Al Davis, who in this scenario was possibly trading FOR Irvin. I'm not sure you can trust the source and regardless, it sounds like this was stream of consciousness type conversation, not a real, serious conversation to trade Irvin anywhere.
Jimmy wasn't always leaving or at least it's not commonly sourced this way. Can you cite you're narrative? Jimmy is a mercurial personality who always judges his situation around if he was having fun or if he was getting bored or complacent or unhappy. Obviously, the relationship with Jerrah was unsustainable and he many times lashed out or responded poorly to Jerrah always stepping on his toes or trying to bully him around his contract. But Jimmy has spoken many times about his personality and how he doesn't look too far in the future but asks himself about his quality of life in the now (below).
The Jacksonville thing was a Mike Fisher story, IIRC. It was about how Jacksonville was interested in hiring Norv Turner for their first HC and the owner approached Jimmy to get his thoughts. Jimmy, in one of his frenzies about Jerrah not respecting him, tells the Jacksonville owner, he should hire Jimmy and Jimmy would try and take most of his staff. The Jax owner, speaking with Jimmy with Jerrah's understanding, didn't like the conversation and never really pursues it. Here's the thing... Jimmy was under his infamous 10 year contract at the time. He hadn't negotiated down it was a bone of contention for the two. Jimmy screaming he'd take his talents elsewhere when Jerrah got in his way and Jerrah always reminding he was under contract and he wasn't coaching anywhere else. In other words, it's a fun and juicy story, but there's no teeth. Jimmy was under contract and Jerry wasn't going to let him out unless...... And remember, it's heavily rumored that Jimmy offered Jerrah 1 more year to go for the 3 peat and Jerrah, getting off cheap in the deal decided it time to go on a 3 decade journey of ineptitude to show real football people that he definitely wasn't one of them.