DC just needs to do an Ostrander Martian Manhunter Omni. Double dipping is just not something most can afford to do on most characters. Ergo, using softcover TPBs to strictly gauge interest isn't a comprehensive way to fully know what the audience wants. With his visibility as regular and high as ever due to Supergirl now is the time to put this one/done Omni out.
I watch Supergirl as much if not more for Manhunter.