The quote about European fascists is a fact. Trump also said that statement when he was in Britain. There is an extensive European fascist movement in the UK, Italy, Greece, and France, to name a few. Most of these groups are motivated by immigrants “changing the culture.” In fact, the Brexit vote was largely motivated by this.
In response to your second question, yes. Those issues also affect immigrants and people in developing countries. As I mentioned, I’ve seen this among the rising Nigerian middle class. My cousin told me now many people choose to have one child, because it’s so expensive raising and educating children.
Non-whites tend to have higher birth rates. This is fact:
But once they settle in the West, their birth rates decline.
The main point of the article is that yes, the white birth rate is declining, but so are other groups, but just slower. The main problem is the cost of raising children.