Except for the fact firstly of Israel and secondly the ultra-Orthodox who almost never “marry out” and have very large families.
Quite so.
The “minority group” to which I was referring are American Ashkenazi secular Jews. The Orthodox can take care of themselves nicely, as you say.
Over the last century Jews, as a group, have dropped from about 3% to 1.7% of the American population. It seems likely intermarriage and assimilation and disappearance into “white” America has been at least a contributing factor. Other factors probably include a low birth rate among secular Jews and increased immigration from other groups.