This is why Jewish children HAVE to go to a religious school. If kids are sent to a secular public school, they will grow without Torah (a couple of hours on a Sunday is not sufficient Torah) and they will become accustomed to non Jews and non Jewish ways. Then when they are grown, there will be no reason for them not to intermarry. Without Torah the only reason not to intermarry is racism. For the record, however, it is a De-Oraisa Torah commandment that a Jew is not allowed to be intermarried. Intermarriage is one of the forbidden relationships in the Torah. Anyone in a forbidden relationship should be scared. It is not safe. Not safe for the Jew and for the non Jew.
Re assimilated Jews - they have lost their Jewish senses and have become so unJewish that they can only think as their non-Jewish neighbors, friends wherever they live in any part of the world, r'l. Only Torah is our true life and in reality, the only Truth! Everything else is an illusion.
But it is what it is ... and pretty unlikely that even the real Jews (that know they are, never mind the ones that don't) are hardly in a position to transform their whole non-Jewish lifestyles, or even attempt to (even if they wanted to). Talk is easy, reality / practicality something else.