My bet is Ben Brown (counterintuitively) leaves the News Channel for a new position as special correspondent, or some kind of new editor level position. He doesn't seem to have a regular slot, and three presenters sharing five shifts a week clearly won't work. That would then leave the afternoon slot to Jane and Simon to share in a similar fashion to Newsroom Live, while also covering the One and Five.
I agree with other posters that it doesn't seem sensible to have a dedicated presenter for the weekend network bulletins - moving Clive to Sundays and adding Kate to the News channel on Saturday evenings would eliminate the duplication, while Martine and Clive could keep similar hours to they currently do covering the evening shift between them on weekdays. In other words, positions might be eliminated and savings reached, without anyone actually leaving the corporation. It's also plausible current NC faces may appear in slots that don't have fixed presenters - like Sunday Breakfast, or various WN programmes.
It's also unclear, as far as I can tell, what the impact is to business bulletins on the News Channel?
I'd like to think Jane and Simon are both too high profile to be let go, unless one took voluntary redundancy. I'm guessing that's Emily now gone from the NC though - does she even still regularly present on Mondays?