This conforms well to the concept of astral planets expressed by Paramahansa Yogananda in his Autobiography of a Yogi and in many other spiritual traditions, also called "spirit worlds".The 5e Spelljammer Adventures in Space depicts the Astral Plane as an "Astral Sea" populated by Dominions, Wildspaces, and various curiosities.
The description of a "Dominion" is brief.
From 4e tradition, I understand the 5e Dominion to mean the same thing as a 3e Outer Plane, also known as the Alignment Planes or the Wheel. There are sixteen Alignment Planes, such as Chaotic Good Arborea and Neutral Good with Chaotic Tendency Beastlands, in addition to the Neutral Plane. Every one of these sixteen Alignment Planes exists as a Dominion floating somewhere in the Astral Sea.
When approaching a Dominion from the Astral Sea, it appears as some wondrous island or floating city, sometimes as large as a planet or as small as a house.
However, these Astral Dominions are regions of thought. They lack the spaciality and distances of the Material Plane. Thus, the amount of apparent space inside a Dominion can be larger than the apparent size outside. The inside of a Dominion can be infinitely large.
The amount of space that is available inside a dream, is the same as the amount of space that is available inside an Astral Dominion.
In addition to these sixteen Alignment Dominions, there can also be many other kinds of Dominions floating somewhere in the Astral Sea.
5e has the best presentation of the Alignment system, relative to all of the editions before it.With regards to characters, I doubt the updated PHB will address alignment much differently than the current version
Yes, to strictly remove any Alignment mechanics solves almost all historical problematics with Alignment., except for to emphasize that it is optional.
The Alignment system is now a recognizable D&D-ism in popculture. In this era of corporate "monetizing", I expect it impossible for WotC to remove Alignment. The hope is, Alignment in OneD&D will be as nondisruptive as possible.I suspect the brief part about "Alignment in the Multiverse" will be cut completely or made an optional rule. It seems like something that is better served in setting book than the base game.
Yeah, spells like "Protection from Evil/Good" need to rename to "Planar Protection", as the mechanics instead defend against immaterial planar Creature Types.And I wouldn't be surprised to see the few spells that rely on alignment reworked.
I sympathize with the frustrations with the alignment system, and the need for many players to easily opt out of it.But I'm also biased because I detest the alignment system and always have. I also don't think the D&D alignment system has much to do with any coherent ethical system.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.