I'm probably alone in this, but I hope the Rise Against pack that is coming out next week is a sign of more Muse content.
With L.A. Rising on the 30th of July around the corner, this would be the time for there to be some promotion for it. Rise Against is the 3rd headliner (after Muse and Rage Against The Machine).
I know I'm probably just setting myself up for disappointment, but I have a feeling Muse DLC might be showing up soon.