Never been much of a Forgotten Realms fan, but I imagine that it would be a pretty good time for a proper FR setting guide. Particularly one that goes beyond the Sword Coast, since one of the only things we've been told is on the docket for next year is a Red Wizards of Thay adventure.
I would love a return to Eberron to give the more mechanical setting elements (species, Khoravar/Jhor'guntaal, dragonmarks, feats, backgrounds, maybe artificer) a fresh coat of paint where needed. Rising from the Last War should still work as a setting guide, so maybe an Eberron adventure module instead?
I'd also love a return to Planescape in the form of a Manual of the Planes-style guide to the Great Wheel cosmology.
Not sure either of those are a next year thing, but I could easily see an FR guide making the cut.