Serums was canceled a long time ago. They are not working on any more powersets for now. They're focusing on QoL updates, new content and new systems.
The main two that i would want are a Shade/Obsidian powerset and a distant second being a Luthor/Cyborg or Steel Power armor. I know Cyborg isn't a power armor guy but he has the similar abilities with the weapons and technology. I know it would never happen, but it would be a good idea for a new weapon style as well. Bunker Buster or shoulder mounted cannon. Like Cyborg's sonic cannon or the two guns on Luthor's back, these guns would be high energy blasts with a slow rate of tire. Depending on which style the devs went with, they could have different attacks animations, along the lines of Mega Man or War Machine. With the current movement of the game, this would also be a perfect weapon to build AROUND power sets, allowing the power to alter the weapon color and blasts, rather than making weapon variants Based on the powers. which they could still do for money. Or, more so, make this a weapon with the first ever (for this game) custom colors. Could you imagine? Using the color you want on your weapons? or even the materials on the beams?