Salaries tend to be sticky. A more likely outcome is the bottom ~25% of engineers being laid off or moved to contract status.
Also, anecdotally, in 2008 some of those fired were expensive new hires. "The bottom 25%" might be defined as those fired but otherwise I don't think there is a definition of "bottom" those who get fired all fit. Say, if a project or a department is terminated, often everyone is let go, instead of trying to keep "the best" and replacing "worse" people elsewhere with them, etc.