In the 19th century people in the US seriously thought the influx of all those Irish immigrants with their weird ways and weird Catholic religion would similarly "dilute" the traditional English Protestant culture of the early US. Now people treat Irishness and Catholicism as just normal parts of US culture.

As the article makes clear up front, the number of people in the USA of working age is diminishing faster than the rate of overall population is growing. Yes, raising pay will bring some retirees into the workforce (is that good or bad for those people?) but won’t materially increase the size of the pool.

If your country’s population is growing you are “giving away” the land to other people, and of course different people have different attitudes…what is considered “culture” changes regardless.

Maybe, but if you aren't begging immigrants to come to America in the next ten years I'll eat my hat. We should be competing for immigrants right now. Unless you like economic stagnation (save for a possible AI productivity revolution).