Shops in France are allowed to be open on Sundays only 5 or so times per year, and they choose the dates. The large department stores are planning to use up 3 Sundays on Dec 3, 10 and 17. I couldn't find the Christmas hours for Printemps and Bon Marche but I expect they will be similar to Galeries Lafayette - closed on Sunday Dec 24. The Louvre is supposed to be open on the 24th, and so the shops in the arcade will also likely be open. Some shops and restaurants in the Marais are likely to be open, as they usually are on Sundays.