There are reasons for possible changes. Some paths in the Wildspace are too dangerous by fault of the Vodoni empire and some giths corsairs.
In the Gatetowns next to Sigil there are planar gates, or something like "bridge/river demiplanes" created for interplanar trade.
New intrusions from the Far Realm. If you are lucky only new Lovecraftian cults trying to summon some forgotten deity, or the elemental eye.
The elemental Chaos of Limbo has became the new Miami, with everybody creating their own demiplane, most of them lord dragons and giant clans, and visited by planewalker explores.
Vecna, like the little children, when they don't make noise then you have to worry. If somebody in the D&D multiverse can cause true cosmic troubles, he is the man. Not even the demiplane of the dread could keep him.
Lots of planes are too dangerous for low-level PCs. Faction war isn't allowed in Sigil, but nobody said about the Gatetowns.
Maybe "cheap" spelljammers are possible for 1st level PCs. For example these only can be used by character with a special feat, maybe being descendant or from the same bloodline of a former captain. Or the spelljammer is almost sentient, enough to rebel against slavery and become rogue. Then the crew aren't the true owners but the allies, because the spelljammer need "XPs" to become stronger.
Some enemies of Vodoni empire tried to cause a zombie apocalypse, and this failed because the undead hordes were....eaten by the werebeasts. Now the theriantropes are furious and uncontrollable because now somebody is using moon rocks for effects as a full moon night.