In my experience, when a package like this is offerred it means a layoff is coming. The company has decided, "We need to cut costs by X number of employees". First they will "offer" a voluntary package which essentially gives "layoff terms" to anyone who wants it. It is better than what you get if you just leave/retire normally, (ex. X months pay, X months medical benefits, etc). So it can be a golden opportunity for those who were planning to leave/retire soon anyway. The company will see how many people take the package voluntarily, then layoff the remaining number they need.
So although it means a layoff, it is generally a compasionate and generous way to benefit some and minimize the unwanted impact to others.
It happened to me. I was going to retire anyway. But by taking an "offer", I got all my normal retirement benefits plus a number of additional benefits. The timing was perfect for me, and it saved somebody else from being layed off.