Count on it, if the scenario really happens.
If an announcement is made that something is coming that would wipe out the world in 6 months, how many people will show up at work tomorrow?
What happens to the plans of the elites to create shelters for themselves in remote mountains (as happened in that movie), if the people who would be making the supplies that would keep the elites alive stopped working? The elites would want people to be unaware (and thus continue working), right up to the last moment.
You’re right.
With all the eyes in the sky though I don’t know how they’d keep it a secret.