There probably isn't a big threat of immediate furloughs if the merger happens. But, mergers typically add a lot of debt to the balance sheet, and when the payments start coming due, watch out. 2-3 years down the road, anyone in the bottom 10% better have a backup plan.
Of course, having a good back-up plan is always a good idea in this business. Flew with a lot of former Eastern guys at NWA that convinced me to keep my military reserve job. Those guys saved my butt when 9/11 happened.