To be fair, the actual sales of her solo weren't cancellation levels at the time, but they weren't very good, just a few shy of 18,000 around the time, trending mildly up, which is unusual, absent any big arc. I get the feeling that Flashpoint and the reboot was an excuse, and that PG just didn't then and doesn't now have any patrons at DC; no one to push for her, which seems to be how it was done there. And probably she was already planned to be a second phase introduction into the nu52 version. So really, blame Flashpoint and the nu52, and the lack of someone important there to push for her.
I think it's pretty clear at this point that she's not going to get her own solo again, not for years to come if ever. Probably not a mini, either. She's probably stuck in the JSA only, so there isn't much character work she's going to get...unless DC does relent and give her at least a mini. I don't know about digital or other platforms; I personally don't think it likely she's going to get any more exposure there than in traditional print floppy comic.
So it's JSA or bust, and even that doesn't seem likely to come next year at all.