Per their own FAQ page,
"What happens if I do not elect in the program? Will I lose my job? Will there be a reduction in force if we don't have enough volunteers?"
"This is a voluntary program that is a personal decision for all employees to consider as it relates to their own career path. If you do not elect to participate in the VRSP, you will continue your employment in the same or a comparable role.
We are optimistic that this voluntary separation offer will suffice to meet our workforce plans. However, if it does not, additional employment actions, including potential involuntary reductions, may be necessary. The voluntary separation offer provides a more generous financial benefit compared to standard involuntary benefits."
So basically they have a number in mind of how many they want to leave and if they don't or they do but it doesn't meet their "workforce plans" they'll still potentially have layoffs, but they're calling them "potential involuntary reductions". So much for "record breaking profits" they brag about at every company meeting...