Short of forcing Westerners into having babies, what do you suppose we could do about this?
Each succeeding generation of immigrants takes on the values of the dominant culture. Western Liberalism is the dominant culture and each succeeding generation of Muslims will take on those values.
This has no history behind it you can refer or point to. We have never taken on large numbers of immigrants from such a radically different culture. And we have never done anything like it in an era with instantaneous, 24/7 radio, television and communications with their homelands, along with the ability to travel back and forth with ease.
Comparing it to immigrants who came here even as late as the 1960s, when jet travel, and even long-distance telephones were both hideously expensive is impossible. They had no choice but to assimilate. There was no television, radio, internet or easy communication with their previous homeland, and even any newspapers were a week or two late and expensive. Now an immigrant can remain immersed in their homeland's culture and language, especially if there are hundreds of thousands of his fellow countrymen and religious fellows here, and tens of thousands more coming each year to swell their ranks.
My neigbour's parents immigrated from the middle east. He was born here. But he started to be 'too Canadian' so they sent him back to live with his uncle and aunt and go to high school in his homeland. He was then married to a woman from his homeland who speaks no English and wears a hijab and robe. His views on women are in line with the Koran, as are his views on gays and lesbians. Last summer, he, his wife, and their three boys went back to spend the whole summer in their homeland. And he has talked about having them spend at least a couple of years there each before they graduate. So that will be the second generation born here, growing up hearing a lot of Arabic at home, watching Arabic TV, going to mosques to listen in Arabic, attending Arabic language events, and going 'home' frequently.
That is far, far different from say, the Ukrainians who arrived a hundred years or so ago, or even the Germans and Dutch who arrived after WW2.