If they need your skills after restructuring, you will be offered your old job back and get to pocket the buyout money.
If they don't need your skills, you're going to get fired anyway.
At least that's how any rational company would handle it. Employees are supposedly hired because they contribute to the company, not to fill seats.
It's very common in these situations to target every org in the company with a goal of X% reduction. If a small fraction of these teams now need extra headcount, easy enough to allow those teams to hire. Usually you don't keep the severance if you return in under X days.
I've personally been laid off, only for the post-re-org team to hire several people, including asking to rehire me. It's rare, and those affected should probably plan to find new jobs, but it happens.
I've never worked at a rational company. I'm not sure that's a thing.