Dark Sun: Doubtful. No coherent psionics yet. No wild talents. WotC adverse to having any sort of limitations to core races/classes in PHB. If it is released it will be a very different setting to 2E and 4E versions. I don't see it this year.
Setting search Part Deux? Why not do another contest to find the next Eberron? Nah I don't see this.
I don't see other settings being resurrected as campaign settings. I can see many being used as references for Ghost of Salt Marsh collections, but actual settings?
Wild talents are in the current Psionics system... just take a feat and not use a Psionic class. Pretty simple. It isn't called out as wild talent but for example my wife took the telekinetic feat and is a Circle of Spores Druid. That pretty much amounts to a wild talent.
I could easily see Greyhawk being revived in the same way that Strahd led to the ressurection of Ravenloft as a setting, Saltmarsh could easily lead to the revival of Greyhawk in a similar vein. It won't be this year though. It might even be after another FR regional book.
I don't foresee a full scale Spelljammer revival myself. I see Spelljammer rules being put into a rule expansion. Right now we've seen zero playtest material related to Spelljammer or Spelljamming but have seen lip service. If we do see Spelljammer it would being in an EVerything guide or planar book.
Mystara? Ain't happening. It failed in 2e and was supported for so long in B/X-BECMI because it was a default setting. As much as Mystara fans love the setting it won't be revived.
Planescape... without the factions the setting is "diminished" quite a bit as the largest part of the flavor of the setting was defined by conflicts of the factions and they already covered the Blood War in Mordenkainen's Tome of Foes. If they do the setting it will be a Manual of the Planes style book with a big section on Sigil.
When . It's probably not this year though because the drama that happened with Weis/Hickman and were they to do it they would want synergy with the new novels. It will be more of a based on how the novels are received issue than a "we are doing this" and then if they are poorly received they will wait a year or so to put them out. I think it will be a campaign because they can do a 320 page campaign book with 90+ pages for the setting & subclasses for the Knightly orders and cover what's needed very easily for non-default campaign use. WOTC doesn't seem to want to do full scale support of any setting and Dragonlance is more of a story setting than other worlds.
My prediction for the other two setting books therefore is Dark Sun & Forgotten Realms. Dark Sun will have expanded Psionics rules in it based on Tasha's. A fuller Forgotten Realms has been in high demand since the SCAG, there is a new BG game coming and it would require very little in terms of playtesting or additional rules content. It will be the same scope, maybe smaller, as the 3e FRCS and account for updates to SCAG and probably the material from Waterdeep and Baldur's Gate since WOTC has shown they do not mind reprinting material and these are the major cities, alongwith Neverwinter, for the setting. In spite of some opinions often expressed in the forums, an FRCS can and HAS contained everything related to the main continent and adventures, as we have seen, can be used as regional guides. It won't have Kara Tur or Maztica because they haven't been touched in almost 30 years and with the current political climate would require massive rewrites so they will leave them alone. If we get an eastern flavored book it will be Magic related instead. Subclasses would be minimal with some reprints like Purple Dragon Knight but since the rulebooks are all default Forgotten Realms it's kind of moot after all.
I already mentioned this Draconic book prediction in a previous post but it would make sense for it to be up next. There are other draconic races, they can expand on the Dragonborn, cover dragon lairs and other draconic species like the gem dragons, shadowdragons, purple dragons, etc. including Draconians as "not Dragonborn" stand ins since... they aren't. It could even be the book where they combine the Feywild material similar to how they did Mordenkainen with Fiends and race development for the common PHB races. It would make sense as well. We could get more Archfey specifically spelled out like Oberon and Titania. I would be all over this book.
I also think we will see an Elminster's Guide to something... if not this year then it will be the title of the next book.
Are we expecting five or six books this year?