This is an interesting question. As time has passed, I think that teenagers gain different insights into Holden. One of the most overwhelming elements that teenagers can learn is the need to forge some type of healthy connection with others. Teens could certainly concur with the idea that the world is filled with "phonies." Seeing Holden's narrative develop, I think that teens could understand the basic idea of the need to connect with other people in order to make living in this world a bearable construct. Teens need to grasp the basic idea of forging healthy connections that allow one to feel at ease with so much in the world that makes one feel ill at ease.
I also think that teens might feel that one element that is interesting to note is how Holden really only challenges "phonies." For Holden, there is only one group or clique, and that are "the phonies." The dynamics of teen relationships are ones whereby there are many groups or cliques where navigation is critically important and an overwhelming challenge. From the novel, teens might be able to gain insight into how important it is for teens to actually seek to breed solidarity with one another so that the real group to target are "the phonies." In a modern social setting whereby there is so much stratification and division, a collective and cohesive entity might allow for a recalibration of social focus, providing hope for so many teens who struggle under the weight of social division. It might be interesting gauge their reaction to such a notion that comes out of the book.