With Big Dave saying the plan right now is the divas only being on one show and getting two world titles... the only belt/s being talked about to go to both brands is the tag belts, and my theory on how they get there is the following.
On the draft night the GMs will prioritize picking the current champions, and there will be a big moment where one GM picks a member of The New Day (who will still be champions) only for another GM to pick another member. (Kofi and Xavier on one brand, Big E on the other) so they'll split up in theory, but they'll stay together as long as they're champions.