While I'm not necessarily a fan of adding more Elemental sub-species (because 5e24 already has a lot,) I think there may be a way to lean Dwarves into the WoTC vision in a different way: start from the perspective of Mag8c the Gathering's mana colors.
•Dwarves tend to be associated with mountains, so Red would be their primary.
•Other sub-species, cultures, and etc could branch out from that and ponder what that primary ("Red") culture might look like (and how it might change) when mixed with other colors of mana.
•Red/White - mountains tempered by plains might produce something similar to what we're "Hill Dwarves." Less Isolationist; More Rural; Generally Good Natured
•Red/Green - This might be more of a subculture within Mountain Dwarf society. These are dwarves who embrace their mythic connection to earth & stone. They understand that Dwarven industriousness needs to be balanced against caring for Mother Earth and Father Stone, for an anvil is of no use if there are no resources to smith.
•Red/Black - these are dwarves who have, to varying degrees, either given into their darker impulses or been forced deeper into the morass of morality. This could include things such as Duergar & Derro.
You get the idea. It's a vague and rough idea, but perhaps a different lens through which to view dwarves might lead to fleshing them out in a different way.