There is a very useful comparison not being made. Orthodox Jews in NYC vs. Orthodox Jews in Israel.
In NYC, the Orthodox used to live in very closed communities, generally outside of the American cultural norm. But today their communities are very open and integrating (compared to what they were). This by itself may explain their declining marriage rate, as well as smaller families.
In Israel, many of the Orthodox live in very closed communities. Very isolationist, they have a very high marriage rate as well as very large families. If it continues another few generation, the Orthodox will start displacing Israeli Arabs, whose birthrates have lowered to just replacement levels.
An interesting note is that both groups use the Internet, but the Israeli Orthodox use it exclusively for business.
I concur. I’ve heard it unironically suggested that it’s during the times of greatest alienation from society at large that Jews flourish as Jews.