I've seen other people post that they thought the concept art might have been the interior of the ark as well. We won't know of course until the game releases, but I think it is fairly likely.
We're going to need a new hub of some sort since the Citadel will be left far behind, and what little information has been released/leaked about the game suggests that finding new home worlds is going to be a large part of the story, if not the main plot. It is probably safe to assume then that the game will begin without there being any Andromedan planets settled by the Milky Way species, and as such it is also fairly likely that the ark is going to function as the main hub in the game.
Awhile ago, I posted about the design of the "Presidium-like" concept art they showed, and specifically that while it superficially looks like the Presidium, it is in fact extremely different. It is not a Stanford torus, as the Presidium is, and the ground is at an oblique angle to the presumed central axis of rotation. The only way that this would work in an artificial gravity sense would be if there was a combination of rotation around the central axis, and linear acceleration parallel to the axis - ie: A starship, not a space station.
And so I find it very likely indeed. As we know that they borrowed inspiration from NASA's old engineering concept art before, it is worth noting that the design is somewhat similar to a modified Bernal Sphere, which again, is one possible real life starship design.