I think if one redefines "Jew" as "Eastern European Yiddish-Speaking Jew," the Nazis were very successful. A few stragglers made it through, but the nation is dead... ============================= I think that's very true. The East European Jews lived in their own communities and had a distinctive Yiddish-speaking culture, qualifying them as a nation, albeit an oppressed one which didn't enjoy sovereignty over its own territory. That Yiddish-speaking nation was destroyed, replaced by a new Hebrew-speaking nation in the Mideast. Elsewhere, Judaism is simply a religion like Catholicism, it adherents dispersed among many nationalities. Swedish and Algerian Jews are still bound by the ancient religious rituals and symbols, but that is about all they have in common.
Many secular Jewish-Americans still identify themselves as "Jewish" but like Irish- or Polish-Americans this tie is purely sentimental. They mostly don't live in Jewish neighbourhoods, speak a distinctive language, go to synagogue, or have any strong involvement in Jewish organizations. What they have in common, apart from some fading ethnic characteristics derived from their Yiddish-speaking ancestors, is a more important collective memory of the Holocaust.
The traumatic fear of another Holocaust has slowed the assimilation of Diaspora Jewry, and allowed the "Jewish community" to maintain an ideological coherence despite the geographic dispersion of those who identify with it. It's built around support of Israel as a potential refuge. Of course, the Zionist organizations have a strong interest in perpetuating the myth of a Jewish "nation" whose homeland is Israel.