So we badgered Brad in the production forums over at the official Vanguard: Saga of Heroes forums until he finally posted. This is what he had to say:

Our second title is very much in its infancy... I can say that it's a game and property I've wanted to see in an MMOG for a long time, but at this point, it's far too early to even hint much at it. Right now we've got to make sure Vanguard is a success, that we get into beta smoothly, and then launch, and then making sure the live and expansion teams are set up right such that we keep marching ahead... we're fully comitted to Vanguard in the long term.

Well, now we're all wondering what it could be! I'm praying for Stargate Online. Add your two cents here.