Parmandur
Book-Friend
Thinking about it deeper, the female cleric has to be a drow cleric of Eilistraee in Skullport and Undermountain, because each Endless Quest ties into an AP except CoS because that occurs in Ravenloft and they might not be allowed to use Ravenloft for the way Endless Quest books.
So 4 remaining APs (Tavern of the Yawning Portal is a collection of adventures not an AP so it doesn't count), all of which has a connected Endless Quesr Book including the current AP, Waterdeep: Dragon Heist.
And what is the next AP, we already know it, it's Waterdeep: Dungeon of a Mad Mage, which is set in Undermountain, where Skullport dwells, and which has been and likely be again the location of Eilistraee's main temple, and Eilistraee in some last editions (but not others) has shown a preference for female priestesses. This explains why the location was so important and why the gender of the cleric mattered and tied into the location.
Which means the Swashbuckler will be for the AP afterwards, Swashbucklers suggest pirates, or at the very least Naval, likely to be released in the Summer, late spring at the earliest. And we have no less then 4 story lines occurring on the swordcoast, too many for the Swordcoast to be likely,
only 2 APs occur else where, CoS in Ravenloft, Barovaria, and Tome of Annilitation in Chult, neither of which we are likely to revisit.
That leaves the coastline of the Shining Sea, which has never been a major FR region or amount the most popular, an Eberron Campaign, unlikely it's too soon and the play testing is still going on, Ravnica doesn't have the open seas, and Ravnica and Eberron aren't on Faerun and I don't think they want to leave FR for the Endless Quests books right now.
That leaves the Sea of Fallen Stars ladies and gentlemen by the process of elimination. The location I think most of us wanted for the style of campaign we wanted that offered a new and fresh type of story. Which means if the next Endless Quest book is their so is the next AP.
I hope the AP comes with a map as detailed of the region as Storm King's Thunder did for the Swordcoast and North.
Dragon Heist and DotMM are ethe same Storyline, Waterdeep. These books don't tie too closely to the APs themselves, so they don't cross the Streams.
I think the Cleric bit is about the next storyline season: but time will tell.
Nothing about a Swashbuckler necessitates a sea setting: Robin Hood or Zorro could just as easily fall under that subclass heading.