I think you underestimate the deeply engrained, now somewhat dormant, fundamental aggressiveness of the Western population when push really comes to shove.

And I'm afraid that situation may arise a lot sooner than many bother to realise. As the rationale of a post-fossil-fuel economy dictates we downscale it towards more less a bio-based one....One capable of feeding roughly 1/5 of it's current numbers.

Humans will then do what humans always do and every minority will then be at risk. 30% might put up an good fight but eventually too will lose. And don't forget that many immigrants still own properties in their former countries and will prefer safety over fighting. So not quite the numbers you can fully count on.

I believe the only way out is to radically reduce our current population numbers so much so that we reach the point that every hand left is very much needed and more than welcomed regardless of colour, creed, gender and age. Seeing that MIC-led NATO (Eisenhower did warn us) is dead set on starting WWIII for profit, I think we might get there too a lot sooner than we dare think... At least it will be a quick death for most instead of by the hand of the extended civil war we are currently heading for.