If I remember right, one of the surveys, about a year or so ago if I remember correctly, had questions on settings. I would assume they would go off of those results. Unfortunately, unlike the previous one, we're not privy to the results...
Yeah certainly, but I think it's a mistake to think that they're going to just publish things in order of established popularity.
For one thing, doing so means fewer guaranteed sales down the line, compared to taking some minor risks mixed in with established popular choices each year. Wizards is very much trying to focus long term and make sure that 2028 is DnD's best year ever, just like last year was, just like the year before was. Publishing everything that people are clamoring for the loudest as quickly as possible is not how you do that.
Second, we know they are down to take some risks with setting books,
and that they are listening to more than just "what old settings are most used by current groups". They put out a Feywild book because they know people want to use the Fey more. If they decide that Nentir Vale or Mystara or Ghostwalk will serve some desire in the community that they keep hearing about, they aren't going to care where that setting sits on the heirarchy of most played existing settings, they're going to focus on how Nentir Vale or Mystara serve the desire to play in a world that is mostly figured out but has a ton of space to explore and to plop down published adventures without any real worry about how it fits, or a world that has a core to build off of to more easily create a homebrew setting that feels like core dnd without being beholden to a bunch of canon, or to have a world that evokes that old (very ahistorical) pop media idea of The Dark Ages as a time just after the light of Rome had winked out and left Europe in the midst of a terrible darkness. Or whatever.
They know that one thing they need to do is provide things that will make people say, "I didn't know I needed this until I saw it".
Remember, they want 5e to be evergreen. They want to avoid ever making a full new edition. They have a strong history at this point of not pushing out everything people are asking for as quickly as possible, but staggering it out and mixing in new things that they think the community will like or that new playerss see as a lack in DnD, as well.