I think Toronto would be better off trading Halladay this off-season rather than waiting until next year. Draft picks, while a nice incentive to hold on to Halladay, are never a sure thing. Taking established prospects or young MLB-ready players would give the Blue Jays more of a sure thing. It's always easier to look back in hindsight, but what the Blue Jays should have done is trade Halladay back in July when his value was highest and the team that would receive him would have him for two pennant races before even thinking about his impending free agency. Since they haven't done that, they should take what they can get for him now.
As for possible destinations for Halladay, the Red Sox, Yankees, and Angels are all said to be interested in acquiring the perennial Cy Young candidate.