The rapid rise and fall of the Moral Majority, the Tea Party, and countless militia movements in the US and of Ukip in the UK are further evidence of the ephemeral nature of such movements in today's society.  It's true that the discontent that gave rise to such a movement may well continue but this only serves to provide the environment for the rise of successor movements, one after another, in quick succession.

All Manning is really saying is that there are a lot of frustrated, anxious angry people out there who can be rallied into a succession of populist movements by charismatic leaders.  He really has no better recipe than anyone else for channeling such energy into productive ends.