My guess could be that they might be using this opportunity to trial different people in the roles, similar to what they did when Fergo was on extended leave, with Angela doing weeknights solo, Angie and Usher doing weekends together, to see how ratings change or how the presenters perform.
Obviously, I hope they leave Ann in the chair for as long as she wants to be there, but obviously, there will need to be planning for when the time comes.
When Jane Doyle left, she gave them 18 months notice so they could do proper succession planning, which is what they did by quickly swooping on Will Gooding’s. Maybe they hired Katrina with having her eventually take over Ann’s roles.
But obviously this is speculation and I could be entirely wrong.