It is very vague, but I'm glad to know we can soon shed that feeling off of "TOONAMI IS ONLY LITTLE BOYS' SHONEN"! I am a tad sad that this means Re:Zero and the like won't be coming, since Re:Zero feels like what Toonami has aired for the past years so far.
My guess is that they're going to air some Western action cartoons again, or at least one. Maybe a PREMIERE! Or maybe more seinen.