How many titles with "crunch" without previous UA articles?
Dark Sun in 2023 is possible, but the primal-punk look can cause troubles because some artists working for comisions could complain if some designs may be plagiared.
My opinion is Planescape can arrive before as compilation of adventures than a new planar handbook. Spelljammer as player's handbook can arrive before, and we can bet for a (relatively ambigous) reboot like Ravenloft. This setting is the ultimate sandbox, where you can add a lot of new things without worring about a "jumping the shark" effect. It is the perfect space where WotC can introduce D&D version of other Hasbro's franchises, for example maximals and predacons disguised as D&D creatures. If Hasbro wants an intercompany crossover between D&D and a no-fantasy franchise, then Spelljammer is the right place, for example one of the crystal spheres is a undead post-apocalypse, the darkspace, but if chronomancers travelled to the past to kill the vampire who caused the cataclysm, and then the time paradox would be an effect like the famous Schöringer's cat within a box, yes and not simultanealy. Then the undead darkspace would be like a mirror demiplane next to the rewritten timeline. Or there is a secret planar gate in the darkspace to the demiplane of the dread (Ravenloft), allowing some dark-lords almost to escape, but they are teletransported into new dark domains within the Darkspace, with life (farms, hunt, forests and about that), a maybe a softer curse/punishment, but the siege of the undeads.
If Spelljammer returns, my suspects is the Astral Sea will replace the old "Wildspace".
And Spelljammer can show places not too dangerous for low-level PC compared with most of the planes.
Using the bionoids (spelljammer creature) how to create a mash-up version of Power Rangers with any touchs of Inhumanoids, hakaiju(horror manga) and Guyver?