The four year decline in the real earnings of college graduates is bad news for their professors. The past 10-15 years has been a golden age for college faculty--there was a strong demand for their primary product (college graduates), who were willing to pay steadily rising tuition to get the crucial diploma. As a result, real salaries for continuing faculty have risen every year since 1982.
As we can see in this chart, real faculty salaries tracked real earnings of college graduates (B.A. only) very closely through the 1990s.
But as college grad pay has started to drop, faculty salaries have continued to rise. This divergence is unlikely to last. If real college earnings continue to fall, the hot and heavy demand for college is likely to slack off--and the golden age for college professors (and their pay) will come to an end.