At least the version of the Eberron setting that I know, is *objectively* agnostic. So conflictive views are possible, subjective, and equally valid.
I hope Modern adopts multicultural cosmological possibilities as well.
Dark Sun works best when it is nontheistic, and survivors are left to their own devices. There is no deus-ex-machina that can swoop in to save Athas from the consequences of arcane defilement.
It is better if the 5e canon makes Dark Sun officially unrelated to the Forgotten Realms multiverse supersetting, even if giving variant options to subsume it into supersetting, for example, transporting characters from Forgotten Realms into Dark Sun, and visaversa. An other variant, might suggest how to make certain Forgotten Realms options as having always been part of Dark Sun, even if exceedingly rare.
The main problem with assimilating Dark Sun into the multiverse is, then the polytheism becomes *objectively* canonically true, while the Dark Sun setting, tone, and feel, becomes *objectively* canonically ignorant of the truth. The cosmology is the context, and context determines meaning, and the wrong contextual framework destroys the setting and what the setting means and implies.