Mercurius
Legend
In my experience Forgotten Realms fans are just as geriatric as Dragonlance fans. NWN2 came out 15 years ago, so the people who grew up playing it are in their 30s now. BG fans even older. Exandria is what is familiar to 2020 youngsters.
You think there is strong correlation between video games and RPGs? I honestly don't know, as I've never gotten into video games beyond the odd foray into Tetris and this or that app.
But my point remains: The huge cohort of new players have almost all played in the Forgotten Realms, simply by default (as most story arcs are set there). They know what it is. Most of them don't know about Greyhawk or Mystara or Dragonlance, or probably even Planescape and Dark Sun - except through rumors. This isn't unlike how most of my cohort--the "D&D boomers" of the early 80s--didn't know much about Blackmoor or even Wilderlands, at least at first, until they were republished in some way, and/or if we went looking.
This is why I'd love to see WotC offer a series of articles through the website or Dragon+ that essentially introduces the "legacy settings" of D&D, and even does some polling to see which settings readers want to see more of. This would be a decent way to gauge interest in older settings, beyond guessing.