His magnus opus was The Decline of the West published in 1918, over a hundred years ago.
Spengler died in 1936, before WW2.
From wikipedia, Spengler made this prediction for the future was this:
Spengler predicted that about the year 2000, Western civilization would enter the period of pre‑death emergency whose countering would lead to roughly 200 years of Caesarism (extraconstitutional omnipotence of the executive branch of the central government) before Western Civilization’s final collapse.
Thus Spengler saw the West in a sort of death throe of the Roman Empire … the age of the Caesars. (I suspect, that the ages of the Caesars came because of corruption and the Jews must have played a role in the destruction of the Roman Empire … but exactly how and where is a deeper question).
However, as we know, despite the incredibly bad thing that was the collapse of the Roman Empire, whites as a race, despite the intense ignorance thrust upon it through Christianity, managed eventually to arise. And our greatest achievements have been since the Renaissance, when we rediscovered our science and knowledge from Pagan times.
Thus despite the tremendous collapse of Rome and the unbelievable levels of ignorance foisted upon us, through Christianity and "be like a child" and "love your enemy" mentality – both of which are idiocy of the highest order … we have lived and survived. What has mainly helped us is our devotion to science and technology. Our tools and technical knowledge saved us.
In Liberalism, we are very likely in an area almost as stupid as Christianity brought upon us. Yet, we can outlive that too, through Science, Technology and a restructuring of our society.
I see no reason why this is the end.
BTW, Spengler predicted that Germans would never produce another Goethe, but they might produce another Caesar … and in there, he was dead right. He did not see it, but Hitler was the Caesar… Remember, this book was published in 1918 and 1922 …. long before Hitler arose.
The Age of the Caesars, is the Age of War. We must welcome this. This is the Age where the Pagan and the National Socialist and whichever Christians are finally ready to fight, can rise up and smash our enemies and put countries right.
Since Spengler predicts 200 years of Caesars, then that’s great. This will be more than enough time to reorganise our race.
Spengler also said that if the White Race stops fightings, then the blacks will continue fighting, and then THEY WILL DOMINATE THE WORLD!
Therefore, White man, pick up your WEAPON… The Age of War is at hand… and we must NEVER STOP FIGHTING UNTIL THE END OF TIME.
This is a conclusion I have formed myself, that the ONLY WAY for the white male, from now, until the end of time, is WAR. Either fight war and WIN or be CONQUERED. There is no other way out.
But we have fantastic tools, and we can create unbelievable things.
Spengler predicted that money will destroy democracy. It is inevitable.
Therefore, everything is good, war and chaos is coming … this is where we whites shine out like bright stars. We will NOT be interested or concerned in VOTING … we will vote with our bullets, shells and bombs. We will vote until we are the majority.