When the market turns down freelancers are the first to feel the pain. Outsiders who assume freelancers replace employees are wrong , at least at first. What happens first is that freelance work is eliminated, then jobs are cut. Freelance is only hired back after an uptick in work, when the remaining staff is stretched and the employer isn't yet certain it's safe to hire again. There are other ways for freelancers to see a downturn.
Employers start demanding copyrights and eliminate residual payments.
Another, more direct, assault against freelance income is the no-compete clause. In my case, when ClickZ was acquired by Internet. Com I immediately lost my weekly column on Andover. Andover competes with Internet. Freelancers are the canaries in the mineshaft for full-time employees.