Why will the Mets get Roy Halladay?
1. Alex Anthopoulos is just like Bill Smith(the Twins GM) in that he has a pitcher one year from free agency he knows he can't re-sign. He wants to get something back for him, rather than lose him to free agency without so much as a draft pick.
2. He's not really serious about trading Halladay within the division. Why would he want to see Halladay in a Red Sox or Yankees or even Rays uniform potentially 6 times a year, when he's trying to compete against these teams a combined 54-57 games a year?
3. He'll thrive in the NL. The National League is a much easier league to pitch in than the American League, with no DH.
4. Citi Field is definitely a pitcher's park.
5(and finally). The Phillies aren't interested. They don't have the money to sign Cliff Lee to a long-term extension(which they will do), and trade their top prospects, plus give him the extension he wants. It's just too much to ask of the defending NL champions.
Look how Omar waited out the Twins, and fleeced Bill Smith to get Johan. I think he'll do something similar to that this time around, to make the club better, and to save his job.