I'm OK with these elves, and I think 5e has been doing some interesting stuff with the cosmology of elves (at least until they send Mordenkainen's Tome of Foes into the memory hole).
I agree that thematically they shouldn't have darkvision but I doubt they will remove it since that is a core elf trait in the PHB, and even though they moved away from subclasses in favor of full writeups for each race, I think they will want to maintain continuity with the core race, at least until the new PHB in 2024.
The point of deleting the design space of a "subrace", is each family of races, including the elf, can have each race be completely different from each other.
There is zero obligation to conform to the Players Handbook subraces.
If darkvision makes so sense, the particular elf race should be free of it.
I am unsure where the Tome of Foes lore will go. (Actually it does have some concerning issues, such as the only prominent nonbinary figure being a terrible dysfunctional parent. No character should be perfect, but problematic stereotype does concern.)
Anyway, maybe the future lore will perhaps work out as follows.
Corellon is a regenerating shapechanger who, thereby, parthenogenetically reproduces children from blood.
In some kind of family conflict. Some remain with them in the astral dominion, some follow Lolth into the material plane. And some relocate to the fey plane.
In the material plane, some then split away from Lolth before descending into the Underdark. Thus the material elves divide up into udadrow (Lolth gish), aevendrow (remain magic), and lorendrow (become materially physical). The aevendrow and lorendrow seem to be hiding from both Lolth and Corellon.
The wood elf tire of hiding and split away from the lorendrow, embracing the materiality of the natural wilderness. Some wood elves become sea elves.
Some time later, some wood elves reconnect with the fey elves, becoming high elves.
In the fey plane, fey elves pursue magic in many places, sometimes immigrating to elsewhere: astral elves, shadow shadar-kai, even into the material plane, as pallid elves, and 1e grey elves and valley elves.
Most of this diversity is evolving into different cultures. But there are at least three salient races with different features.