Greg Mankiw proclaims in his blog that it's a "media myth" that long term jobs are disappearing. Based on a report by Ann Huff Stevens:
Stevens uses data from surveys of men aged 58-62 who were quizzed at the end of their working careers. She finds that in 1969 the average tenure for men in the job they held for the longest period during their careers was 21.9 years. In 2002, the comparable figure was 21.4 years, not much different. Just more than half of men ending their careers in 1969 had been with a single employer for at least 20 years; the same was true in 2002.
The obvious problem with this survey is that it tells us what the labor market was like for men who were born in the years 1940 to 1944.
What's the labor market like for men born in the 1960s? The 1970s? The 1980s?
The company I do work for pays me only as a temp because they don't believe in having permanent computer programmers on staff. They intend to get rid of me as soon as they replace the software I work on with something they think will be better.