Pearl Abyss has stated that they are creating raid content for Black Desert Online. No details have been released at the moment.
Q: Are there any plans on releasing dungeons or any raid instances in this game?
A: Yes, there is! We are planning on a various kinds of dungeons in this game. We will have a lot of solo and party dungeons that are very challenging. We are also working on raid dungeons that will require a bigger party.
Quote taken from Steparu’s interview with Kim Daeil. 19 September 2012.
A small teaser of the mighty raid boss, Keujakara, was seen in the 2012 official trailer.
I believe Keujakara is, indeed, a true raid boss and not a 5-man instance boss. See this Japanese interview with 4gamer:
4Gamer: So, which elements of the game will truly involve the “massively multiplayer” aspect?
Mr. Kim: We will have parties, guilds, siege warfare, and raid bosses. The huge monster in the second half of the trailer is a raid boss.
In the original Japanese interview, Mr. Kim uses the word “レイドボス”, which is a colloquial term for “raid boss”.