Like HC, I'm recently retired having spent 2 years with the "original" and 35 with the "colonials." That's a long time to observe "The Good, The Bad, and The Ugly."
As observed above, problems mostly originate at the middle level. Sometimes people are let go and it doesn't seem fair. Other times, management goes out of its way to help an employee out. I know of one time when a big boss found out a pilot, through no fault of his own, had a massive medical bill, and took care of it to the tune of close to 6 figures. Pilots who were grounded and had used up all their sick leave were put to work doing other things till they could get up to snuff.
Frankly, it is middle management that takes the brunt of the downside - they aren't protected by the CBA - and when it is decided that it isn't working out, well, it's not always pretty.
As far as layoffs - lots of variables. Covered by a CBA? If not, then overseas postings available, licenses required, etc.
Bottom line is, do your job, keep your nose clean, stay out of management and hope for the best.