Justice League kind of failed because CN was mostly watched by kids. And the DC characters were NOT interesting then. Superman was a straight-man. So was Wonder Woman. So was literally every hero. Flash was even mostly to a degree. The characters werent emotive enough for kids, and the stories werent able to be digestible for kids either.
Today, i think if they upped the edge factor, introduced real moral dilemnas (which is when DC is at its best) and stopped focusing on tired Batman or bland WW, then it would work. Actually, just reboot it and make everyone more interesting.
ORAS secret base: http://imgur.com/V9nAVrd
3DS friend code: 0173-1465-1236