Yes, they were told a full year in advance that there position was being eliminated.
(Note: I wouldn't used "fired" in this example. The people didn't do anything wrong, which is implied by "fired." They were laid off, let go, or more accurately, as I said above, their position was eliminated.)
You can do things with an hour's notice, yes. A day's notice. A week's notice.
It's common in the US that when you leave a job, you give your employer two weeks' notice. That allows for an orderly transition of your projects to other people. Of course, if you are going to a competing organization, they may not want you to work those two weeks. They tell you to just stay home.
Student or Learner