If Zendikar and Ixalan can both be "adventure world" and god knows how many artifact theme worlds they keep doing, I think Dominaria can share some of the "history" flavor without it being diluted. The fact they seems to be more modern but magical tone also keeps it from stepping on the more epic fantasy/science fantasy feel Dominaria has.
You kinda have a point there. Then again, there have been weirdly specific cases where they tried to be different just for the sake of being different, like the Orzhov/Cabal scenario. Or take the fact that they are burning through design space for Sagas at an alarming rate, a card type that is part of the Historic mechanic, both of which were introduced to convey Dominaria's new history theme. I'm pretty sure that, between Theros and Kaldheim, most Sagas that have been printed so far are now from planes other than Dominaria, and I'm kinda worried there might be no interesting design space left when we return there. Which would be doubly frustrating because you can't do Historic without Sagas since they are directly referenced by that mechanic. Considering that it took them forever to come up with a modern identity for the plane, and also considering that only led to one set after an eleven-year gap, I've become pretty touchy and protective on that front.
And when you think about Dominaria outside of the 'magic academy' and 'university of archaeologists' context, there are more aspects and regions of the plane that are probably not going to be explored at least in part because the flavour or mechanics that would imply are already tied to another plane. Artifact theme with a magical resource represented by energy counters? That's going to be a return to Kaladesh, not an exploration of modern day Kipamu. Pulp adventures with pirates and mercenaries and explorers on the high seas or in deep jungles? Probably more Ixalan rather than Southern Jamuraa or Dominaria's South Sea. A set about bands of adventurers delving into ancient dungeons? Let’s return to Zendikar ten more times, because god forbid anyone explore those artefact toves from the Brothers' War or any of the old Thran cities. A dragon set with lots of dragons in all colours? You guessed it, it's going to be Tarkir, not a fleshing out of Dominaria's dragon nations and the Primevals, not even another shot at what
Scourge was trying to do. Maybe I'll be proven wrong one day, but stuff like that frustrates the hell out of me. I'd argue we have too many planes as it is, especially with the rate at which they've been introducing new ones lately, so why do they constantly ignore all this stuff that has been a part of Magic since forever in favour of some new plane? And it's not even just Dominaria, I already mentioned the wizard school on Ulgrotha for example.
Don't rule out the Clans of Storgard or the Houses of Estark.
Great, you just made me even more nostalgic for Estark
On the other hand, I already put a lot of love and attention to detail into creating an authentic version of modern day Estark as the starting location for my Dominaria D&D campaign, so I guess getting an official canon version might be a little bit awkward at this point... (Anyone remember
oquorak for example? That ritual combat with daggers the people in
Arena were into? Yeah, I homebrewed rules for that. We didn't even spend that much time there before we moved on to Benalia, all things considered, but it's definitely been set up as a potential future homebase, and the players got to do a lot of stuff you'd expect in Estark while they were there).