Thanks for blogging about this...I missed it and I'm glad to see it.
I do think Deresiewicz's view is bleak, and I can understand the previous commentor's reticence to discuss the next predicted demise of the Jews, but there is something very true, and not too depressing, in his overall statement.
There is a tendency among those who present the Jewish community to the larger world to stress every type of Jew except their own. We look to Israelis, Ethiopians, Russian Immigrants, Holocaust survivors and others as the signatures of our people, without showing any real interest in reflecting the largest, most influential group of Jews in the world: middle class, suburban, ashkenazi, reform or conservative Americans.*
There is no problem with acknowledging Jewish diversity, but I think American Jews some times lean towards diversity because we are, as Deresiewicz suggests, bored with themselves.
Power, wealth and comfort are not interesting, but Art and History demand a focus on who we Jews really are…imagine if the Jews of 19th c. Berlin, Hamburg and other elite, established, relatively integrated and comfortable German Jews found themselves too dull to bother reflecting and documenting?
Basically, for every exotic Ethiopian or Brazilian Jew, we should include the typical, banal American Jew as a vibrant and key part of the community.

*I know there are a few more Jews in Israel than the US, but it is also far more diverse that the US community, so above group is the biggest chunk of Jews in the world.