The cancellation isn't surprising, given CN's narrowing demographic objectives in recent years, but it's disturbing that they don't even seem to intend to air the rest of the series. Maybe Netflix could come to the rescue again like they did for The Clone Wars?
I note that there's a new Scooby-Doo series in the lineup which sounds like it could be picking up from the finale of Mystery Incorporated. That doesn't necessarily mean the same creative team will be involved, but the cancellation of Beware the Batman could free up Mitch Watson to return to Scooby-Doo and make this new show a worthy successor to SDMI. In which case there'd be something positive coming from this, at least. But that's purely speculative at this point.