I think Amber Sherlock might've finished her holidays, since she's presenting Sydney weather tonight.
Personally, I would not rule out the possibility of Georgie Gardner having a week or two off the bulletins before normality resumes later this month.
Haven't we seen Deborah Knight present the news for a week or so before Peter Overton has returned from a break in the past?
Realistically, I would've thought that we'd see Nine promote Eva Millic to weekends if Melissa Downes was to quit?
As for what they'd do for a male co-presenter if Andrew Lofthouse were to ever leave, I really don't know...