I can see Singularity Jain showing up if he does an outer space story, but I can also see her being used alongside some stuff like Suprema, Desira or...
Bringing back Eviless/Saturna from obscurity (along with Crimson Centipede, which is even more out there) earned him soooooo many brownie points from...
Zatara maybe. Other than that, what's the point? None of them took off like Superman did, and it's his 80th anniversary. Why should he have to share...