That is never how this shit works, partly because they can't guarantee that everyone will keep their mouths shut, regulatory reasons, and not wanting people sabotaging shit.
Executives will know because they're the ones making the deal. Upper management may be able to figure out what's going on. Middle and lower management should have a clue of whether or not they're about to be without a job. Rank and file employees, I said this in the bioware thread when idiots there were insisting layoffs weren't going to happen but it's generally pretty damned obvious its coming if you've ever experienced it before, and you can make general observations like hiring coming to a halt when there's still turnover, managers being dragged into excessive meetings with nothing to say about them, progress on projects coming to a screeching halt, and so on.
You idiots will get your communication when you're being walked out. Every damned time with these people "but they promised" did they sign a contract? No? Then they didn't promise shit.