Pretty much. Graphic novels are simply novel sized (sometimes even physically in novel dimensions, sometimes not) comics that either tell a lot more of a story at once or compile several issues of a regular comic into one book. :)

The WoW comics are actually aready compiled as graphic novels. They've only been issued in a hardback form so far, they're the same size dimensionally and use very thin, high quality glossy print.

At this time, I can only assume that they will continue in this method, but I think there's an equal chance they they will be presented in the same manner as the Sunwell Trilogy and Legends novels.

Regarding an earlier comment about Onyxia and how the story in the comic was too detached the game, please remember that there are some things that are just done for gameplay reasons. Raids in general have been slowly dragging primary characters into the encounter in order to tell the story. When WoW was released, this was not the gameplan. The plan was for players to do everything by themselves. This approach is no longer the case. Had Onyxia been released as a pre-wrath encounter, you'd probably find that it would've been set up similar to the story told in the comic. Varien would've been there to help us.

Player actions are not canon. Only the in-game scripts are.