I just want Planescape to be its own setting and the other settings get to do something else.
I re-played Planescape: Torment recently, and it made me realize that the setting should not return, at least not in it's past form.
The first problem is what Planescape was made for, which was to counter White Wolf's clan approach with Vampire: The Masquerade. That's why there are factions in Planescape. It was also supposed to be "hip and cool", and turn everything players thought they knew about the planes on its head. And also take the well-written but somewhat laconic "Manual of the Planes" and make it more interesting.
Like a LOT of things made for 2nd Edition AD&D, there's a lot of "squeezing that square peg and forcing it into the round hole" going on. The setting would have benefited from having its own rules set, but TSR was out of the business of producing different rules for different games at that point. Pages upon pages of rules on how spells work and don't work on the planes, and then they threw in spell keys as a means to just evade it all.
The biggest issue, though, is the Great Wheel doesn't work anymore. It was a product of it's time, and things have moved on since then. Alignment means even less now than it did then. And there's no concept of time anywhere in the multiverse, except as another raw element. Kids and fans have now had the whole multiverse concept explained to them by the MCU, and it's absent.
Finally, don't forget that Benjamin Riggs showed that to everyone's surprise, the setting sold really poorly. So what was done then didn't sell. That means to make it work now, you'd have to change it, and likely that's just going to make people angrier than Spelljammer did.