With these kinds of offers, they don't expect to get rid of 60,000. They expect to get rid of Y,000.
They make the offer to 60,000 (typically, an entire department gets this offer, including people they want to keep). Some X,000 will take the offer. If Y,000 > X,000, they they lay off the difference.
They make the offer to 60,000 (typically, an entire department gets this offer, including people they want to keep). Some X,000 will take the offer. If Y,000 > X,000, they they lay off the difference.