I saw it happening in a funny way not long time ago - company offered buyouts, but got insanely surprised when high percentage of people actually accepted it. Management thought acceptance rate would be much, much lower, but when numbers started to pour in on a 2nd day, oh man... Panic spread very quickly because people were accepting packages in fear of layoffs without such package, so management said if any layoffs will happen in 3 years period after this, same package will be offered no question asked. Cooled things a bit, but what a mess...
And people believed them?!
Probably because they could sue them for not keeping their word.
Unless those funds were placed in an escrow account, I would have assumed that claim held no water.
There's a reason corporations almost always settle lawsuits (if they aren't dismissed).
And?
Litigation is a rich man's game. Companies almost always have more resources to dedicate to litigation than individual employees, especially if those individual employees have been laid off and are now without an income.
The company knows this, the employees know this, the company knows the employees know this, and vice-versa.
Okay, so how many nights until the blue-eyed employees all leave the company? :p
You can't say, "Well, we hired a new CEO, so all those old agreements are null and void."