To answer my own question...I think Crocker and Hansen are the most at risk. Crocker, because anyone could have one off race and he is basically banking on one swim to make the team. Hansen, because he's got pretty stiff competition in his two events (Gangloff and a number of guys capable of low-1:00 or better in the 100, Shanteau, Spann, Usher, Pogioli in the 200). But, more than that he seems like a guy who has been working harder than ever to overcome his "failure" in Athens. I fear he may not be fresh enough come Trials.
To answer my own question...I think Crocker and Hansen are the most at risk. Crocker, because anyone could have one off race and he is basically banking on one swim to make the team. Hansen, because he's got pretty stiff competition in his two events (Gangloff and a number of guys capable of low-1:00 or better in the 100, Shanteau, Spann, Usher, Pogioli in the 200). But, more than that he seems like a guy who has been working harder than ever to overcome his "failure" in Athens. I fear he may not be fresh enough come Trials.