Halladay is a great example. I don't think anything short of a ludicrous trade like Lincecum and Cain would make the Blue Jays trade him.
Guys of this stature normally only get traded if they want a trade or if they're approaching free agency and it's obvious they won't resign with their current team. Jeter certainly doesn't want a trade, and the Yankees can obviously resign him, so he's not going anywhere.
Why is this a question? Unlike many teams, Jeter is a team Captain with a long term deal and a no trade. The yankees will probably pay him beyond his life cycle till retirement since they have not had a pure NYY since since the 50s-60s. He is having a good year so far and looks good for longetivity. He would be the first NYY to hit 3000 hits solely for them since who? Trivia.It's irrelevant since Derek Jeter has a no-trade clause as a 10-and-5 player. I don't see any reason why he'd think about leaving the Yankees, so it doesn't matter if the Yankees would do it. It's entirely his choice. The only way he will leave the team is if they choose not to re-sign him. The same applies to Mariano Rivera, and Jorge Posada (no trade clauses as 10-and-5 players).
As for Rivera and Posada, that is a tuff one. Yanks have traded away their top minors for a while. I could see picking up a closer and catcher next year as stop gaps for the short term. I am hoping Hughes can finally strut his stuff.