Yes, the introduction of Siege Horde challenges will certainly keep me coming back to playing Edain when I'm tired of AI skirmish. Honestly I much prefer playing on my own (and I am also pretty terrible in online multiplayer), because it provides the opportunity to enjoy the beautiful models, intricate play systems, and utilise unusual strategies.
I really hope the Siege Horde maps prove as variable as promised, so that keeping Orcs out of the White City shall feel always like a new threat rising again