Well I agree that it's a pretty pathetic state of affairs to be doing this.
The company wishes to reduce the amount of labour available in the mornings to match the perceived volume of business activity. That's redundancy - no two ways about it. However the payments aren't going to be too much to bear.
What they would prefer to do, of course, it to shift some people to the afternoon. It may actually suit some people - especially if a bit of pressure is put on. I have done this sort of thing myself in my time in HR.
For your wife she needs to work out whether she feels she wants to do this - many part-time wives want morning work because of school-kids returning mid-afternoon so it a countrywide generic problem. If she can fit the hours, then do so. It may also help her case to offer the company to going back to a 2pm finish - either from a 9am start or offering 10am start. That shows some flexibility, and in a 'divide-and-rule' organisation it may help her if things get more difficult.
If they don't get enough volunteers to shift their patterns, I can't guess what they will do, but redundancy for some seems highly likely. Your wife should be trying to second guess how they will do this - LIFO is historically a well-used system - but there is a no guarantee the organisation will use this. Also where she thinks she may lie in the 'pecking order' for out, versus the number of shift (proportion) that need to shift.
She could work out an 'alternative' strategy - by say, sitting it out in the hope she won't get picked, but with a back-up strategy to offer afternoons or weekends, if she gest fingered to be shifted out. It depends how much she wants to job versus the inconvenience of the alternative shifts, I guess.
Hope that helps a bit to understand the 'psychy' behind how these situations develop.