Some more reading into it.
The company decides to make a major restructure to the way the company works. It may technically be called reconstruction. As a result ALL roles at the company are redundant and therefore all the people at the company are at risk.
New roles in the restructured company are offered. Typically it seems that these are near identical but with different titles and different Ts&Cs – how that works legally I don't know but it seems the norm that companies have stood up to challenges on this.
So while we all know what's really going on, it's a fairly straightforward redundancy situation…
And irrespective of that, people usually accept because they don't want to risk not getting a job so sticking your neck out will likely be a lonely and stressful experience. My advice (from some experience of something similar) is to take what's on offer and look for a new job.