Wait, what? Did they announce something?
March of the Machine is making huge changes to the MtG cosmology, like Realmbreaker the Invasion World Tree the Phyrexians have been growing reconnecting the various Planes for the first time since the mending so the Phryexians can invade other planes.
Plus Sylex made have it's own effect, last time a Sylex was used it lead to the shard happening.
And WotC said they'd merge the D&D and MtG if they found a cool way to do it and they thought they could get away with it.
So it seems obvious that with the weird cosmological changes the Blind Eternities (MtGs multiverse) is under going in March of the Machine, that this the opening they need to connect/merge the multiverses.
All they need to do is say have one of the branches of the Realmbreaker push past the Blind Eternities and right into say Faerun. Or maybe have the Sylex blow a hole in reality itself, a hole that leads to the Great Wheel cosmology.
Planescape is functionally about the cosmology of the D&D multiverse, so if you want start the process of integrating the multiverses it's a good time to start ahead of One D&D next year with this product, even if it's just a couple of paragraphs.
Also it seems clear from Spelljammer, Eberron: Rising From the Last War, and Explorer's Guide to Wildemount and the PHB that there is a goal of maxium cosmological merging.
PHB merged the Great Wheel with the World Axis cosmologies, adding WA's Feywild, Shadowfell, and Elemental Chaos to the GW. EE: RftLW found a way to intergrate Eberron's Orrey into 5e Great Wheel's cosmology. Spelljammer added in Wildspace and Divine Dominions as seperate from outer planes, allowing 4e World Axis Divine Dominions and 3e Forgotten Realms Great Tree Planes (possibly others) to be added to the 5e cosmology. So Planescape could continue along this path, targeting Blind Eternities this timem
Either way that sets things up for 2024, D&D 50th Anniversary (by the Gods let it go better then MtGs 30th year disaster), where MtG settings will likely get mentioned in the One D&D PHB, and maybe the One D&D MM and DMG, oh hell maybe even in some kind of Forgotten Realms Campaign Book if a branch Realmbreaker penerates the Forgotten Realms unleashing some Phyrexians.