With a lot of heroes in the nu52 not having a series it might be a good idea for DC to have them guest star in an established book (Batman, Action, Green Arrow, etc.) just to keep them out 'there' and not disappear in limbo. In between story arcs have something like Firestorm pop up in a Detective issue running into/helping out robo-Batman or Batwing chasing down a lead and meeting Green Arrow. Something to help keep the idea of a connective DCU and less isolating between the series.
Or having an artist draw a panel where the hero passes a tv screen showing a news story of a superhero in another part of the world or a newspaper with a headline of another superhero stopping a crime.
Another idea would be for DC to bring back its Daily Planet backpage it used to have done up as a special section of a newspaper. Real newspapers have sections of their paper devoted to local news, national news, sports and entertainment. Papers in the DCU would have a section devoted to all the superhero activity going on in the world. DC could use this backpage to spotlight some of the story lines going on in the various series ('Joker-bot runs rampant in Gotham' or 'Depowered Superman faces down Metropolis police') sprinkled with a few made up headlines ('Captain Marvel stops armed robbery', 'Firehawk prevents assassination of diplomat in Paris', 'Metal Men fight living chemical spill').
Just something to show that even though these superheroes don't have a series they're still around fighting the fight in the DCU.