I'd say that the unions really aren't the problem, (as stated by everyone else) the pay would have come down whether you were unionized or not, it's just a matter of if you'd agreed to it (union) , or it was imposed (non-union) there's also the chance that the union could have voted down concessions. But in which case, the company would probably have gone bankrupt, and restructured anyway, lowering the pay during the process (while awarding themselves a large bonus i might add).
What i see as a huge problem in aviation is that you can't market experience. yes, it's the only thing that will get you the job with Delta, NWA, Southwest, or many other airlines, but pilots are essentially picking what they believe to be "quality" outfits that should be around in a few years, or, picking the best "salary" available. Any most other professional fields, your resume and experience gets you the opportunity to negotiate a pay rate that you and the company feel is adequate. Here, they don't, and as long as you can't, no company is going to fight over getting an employee, you're just another toothpick in the box.