The first world is committing suicide by immorality. Neither immigration nor foreign ideologies have anything essential to do with it. There is a vaccum in the heart of the modern west, and it shows up in empty houses and murdered children.
All that needs to change is for people to decide they love life, their own future, and their children, more than they love their present vices and their idiotic cynicism. If they do, all the rest will be easy. If they don't, no extra dose of cynicism or ruthlessness will remotely help.
How can a people expect solidarity from each other in some fantasy version of a grand historical cause, when in their private living reality they literally flush their own children down the drain?
You have very valid points. But, it is also a psychologcally "a chicken & egg" concept -- "Is the Western world dying because we don't have enough babies?" Or, "Are we not having babies because we are afraid that our world is dying?" I think that the answer to both is "Yes". The question is how to stop this downward spiral -- not just individaully, but collectively, and quickly enough to recoup worldwide (or at least in the US) before it is too late.