It's also spelled out in The Birth Dearth[1], but yes, the idea is much older. It is a synthesis of Hobbes and race to arrive at a conception of racial power which constructs a "looming crisis" extrapolated from a decades-long demographic trend toward racial pluralism. In so far as Wattenberg is concerned, the stakes are western civilization itself by way of an implied western chauvinism.

1. Wattenberg 1987 (ISBN-13: 978-0345343994)