the creator (kodaka), the artist (komatsuzaki), and the composer (takada) are all working on 4 new confirmed projects and they made a new game studio for them with the zero escape creators. theyre working on a game that will likely be similar to DR and since all these games have the same team they could have a similar feel, but DR will not be back.
No, it's not officially over. Kodaka said he doesn't plan on working on another one but he kind of implied that he isn't entirely taking that option off the table. Either way, we shouldn't expect another game for a very long time even if there is another one that comes out.
@othersidk