Back on topic I still say the outstanding issue is reconciling the D&D cosmology with the MtG cosmology.
The default assumption rules of the PHB, MM, and DMG and most other rule books are that I am playing in the default D&D multiverse.
If I'm playing a Satyr in Theros, which are fey and someone casts banishment on me, I find that I am in the feywild of Theros! How will that work in practice.
If my goblin on Ravnica casts Etherealness, they go the Ethereal Plane, which means Ravnica has an Ethereal Plane! Same with Astral Projection meaning their is an Astral Plane. And Planeshift cast on others breaks a fundlemental rule of MtG that has only a few exceptions, that only Planeswalkers with a spark can shift between Planes.
See this isn't a problem for traditional settings, even Eberron resolved this issue. And it's not an issue for Exandia which was build in a sense with this cosmology in mind.
But MtG settings like Theros and Ravnica were designed with the MtG Blind Eterinities cosmology in mind.
Can someone on Toril cast planeshift to the Blind Eternities with the rest fork?
They can't ignore this forever at some point MtG will have to put a ring on it, and commit to a mutual cosmology with D&D.