DJ-PON3 has to be the winner of any Popularity vs. Screen Time chart you could make for most any franchise. And really, she was a fun inclusion to Rarity's doomed fashion show. I couldn't even hold her anachronistic appearance against her (although pinning down a time period for the ponies is notoriously hard... Still, at this point of the show it seemed to be a largely pre-industrial society, so dropping a DJ in there was a bit of a change-up.)
The show runners have explained that she is a full-blown "secondary character" rather than a background pony at this point. Will she get a voice in an episode? I kind of doubt it, but I do expect that she'll pop up sometime in Season 4. Pinkie seems to have her number for big events, after all.