I think this would be a great option for those not fortunate to engage others to play.
Single player campaign available?
yeah...seems like a bit of a missed opportunity to not include solo/co-op rules for the campaign mode (especially now that Descent is getting some rules for co-op/solo play and this seems so similar).
Though I imagine automating the imperial/overlord role isn't easy to do well, it would be a really awesome inclusion to give folks a way to play solo or without one person needing to play the "badguy."
Well, the 'Bad Guy' could be seen as the GM.
Also, single player is possible. You just control both sides. That's how I play X-Wing, which, being a game where your moves are secret, can be less fun than with another player, but hey, at least now I always win! I always lose, too, but I still win.
I can see them putting out an expansion that features a solo game mode. I suspect they already have a solo game mode fleshed out, but they are waiting so they can sell it as an expansion instead of including it in the core game.