Yes, it would always be an option. Still, with 5e now 4 years in, and FRs being the only “official” setting so far, they have a plethora of settings to choose from.

Mearls et al have said directly that they are treating the D&D cosmology as one big Multiverse; there was such a hint in TftYP and ToA, now in MToF they will do it profoundly.

This of course is a huge thing; we might see Planescape arriving in 5e soon, we might Spelljammer and thus we might see other famous settings of old (Dark Sun, Eberron etc). As also, just like ToA, we might see a famous BBEG from other settings rampaging through FR or even team-ups we never imagined happening.

There are no boundaries in imagination.

Do they need it? No, obviously not. I certainly didn’t mean to imply that it was a necessity. I just feel that it enhances my sense of immersion when that sort of stuff is known to the players.

Everyone has their different styles of gameplay and different parts of the game they enjoy. For me, it’s all about setting immersion and verisimilitude first, an awesome story arc second, and cool puzzles/tactical challenges third. Obviously, one has to tailor personal preferences to match those of the rest of the table, but it’s my starting point.

I think I’ve got a handle on Wizards’ strategy for introducing new campaign settings in 5e, and it’s very clever. Rather than have a bunch of segmented settings as 2e had, Wizards is really playing up the multiverse angle, and looking at 5e as one giant setting. I strongly suspect that any book with a new setting, be it a sourcebook or an adventure book, is going to connect it directly to the cosmology as detailed in the three core 2014 books. Eberron, Greyhawk, and Dragonlance won’t be disconnected universes; they’ll be situated in the overall multiverse as casually as Chult sits in Faerun. In that manner, they make sure all books are suitable for a wider audience.

Mordenkainen’s Tome of Foes is almost a Planescape book, but it builds from the cosmology already detailed in the three core books; it doesn’t exist independently.

Curse of Strahd took a similar approach, where Ravenloft is a parallel dimension rather than an independent universe. The players get transported there by a sinister mist; the adventure module assumes that they’re not citizens of Barovia.

Maybe they’ll get really crazy and give us a NEW setting?

If you don’t count the Nentir Vale (which was never given much more than a scatter-shot, sporadic hints at a setting instead of a proper sourcebook) there hasn’t been a new official campaign setting for D&D since 2003’s ‘Ghostwalk.’ Which was only ever intended as a single book…

Well, not only that, the Realms are in general famous as a setting. So chances are people might know some of the lore already from various sources.

Sadly, we do not know yet how they’re going to treat other settings in 5e. My guess is they will keep on making these hybrid books as in FR, but we shall see.

The Realms are fairly easy to grok with only minimal information, especially the more commonly seen regions in and around Faêrun… It’s the Tolkien-y Renaissance-y Generic Fantasy Melange™️ that’s been seen in thousands of other forms.

But when dealing with other settings that are either a significant departure from the default (e.g., Dark Sun), have significantly different tone (e.g., Ravenloft), or where the settings lore/history is going to be a major factor in the campaign (e.g., Birthright) then I think it’s best to make as much of the setting material “player facing” as possible.

Well, I’m totally on board with you about that. But as far as FR go in 5e, most of the PCs in the campaign I’m DMing found all the info in SCAG sufficient. In case someone wanted something more, I prepared a document for him.

Your mileage may vary, but I find it helps for everyone’s sense of immersion if they know as much about the world their characters inhabit as possible. Oh, sure, they shouldn’t know The Kindly Old Man is secretly the head honcho of The Local Demon Cult, or other plot elements… But they should know the geography, history, society and culture of the land they live in.

But, they do not NEED (as PCs) to have that knowledge.