You know what is more likely to happen? Quitting. Temporary leave.
Not sure why "got hit by a bus" as a expression for person is suddenly gone took off. If said person in the room then it is usually followed by something to smooth it over such a "God forbid". How about just hitting the nail in the head with the most likely thing to happen which is quitting or sudden leave. Quitting could be the company, team or life.
I will address every time I hear it because it is egregious and the fact that it has to be followed up with shows that it is. Choose a better way to express sudden departure.