It looks like Square Enix has some sort of Dragon Quest-related announcement to make next week, and it will be a "big title".
The announcement was teased in this week's issue of Weekly Jump. Though it doesn't specifically mention Dragon Quest, it's on a page sharing new details about an upcoming (Japan-only, for now) 3DS port of Dragon Quest VIII. Additionally, the tease says it will make everyone say "Nuwaaaaaaa!", a reference to a line of dialogue in Dragon Quest V.
This has led to speculation that it may be some sort of Dragon Quest V remake. That game was originally released on Super Famicom in 1992, before getting a Japan-only PS2 port in 2004 and worldwide releases on Nintendo DS and mobile platforms in 2009 and January this year, respectively.
Meanwhile, Square Enix is working on the aforementioned Dragon Quest VIII 3DS port and a new Dragon Quest Monsters game, and is also overseeing a sequel to Dragon Quest Heroes in development at Omega Force.
Whatever this new game is, it's unclear if we'll see it outside Japan, as the Dragon Quest series' track record with Western releases is inconsistent. That said, the first six games are all now available worldwide on iOS and Android, and the Western release of Dragon Quest Heroes is on track for release on October 15.