This game really, REALLY does not need any more masters. I would rather see sub-factions get more time in the spotlight than anything. Maybe 1 more Henchman in each faction, plus some Enforcers and Minions, but that's enough for now.
What if the theme was "Collaboration and Infiltration" instead of "SHINY NEW THINGS," and we saw more cross-faction interaction? Henchman that allowed for a single type of Characteristic out of faction? Dual faction enforcers? Why not bring some of the other, older characters from the fluff that haven't been given anything and just develop the main story more with what already exists in terms of top-tier leadership?