Multiple papers now reporting that it will be Nigella, so that seems to be official.
I think she'll be good. She has enough judging experience and confidence to stand up to Paul, and I love her books and food writing. Domestic Goddess was my gateway to baking and I love the way she made baking accessible and enjoyable for busy family cooks. Obviously she has never been, or claimed to be, a professional cook, but she has been a food critic for decades and will know how to talk about baking with insight and engagement.
My guess is they were trying out Caroline Waldegrave to see if it worked, as she is more in the Prue mould, but while she was perfectly pleasant and competent, she didn't bring much presence to the screen and I'm glad they went for someone with a proven track record.
Looking forward to it!