After the Vita version releases, the Vita players will first get to experience a new story quest and a new boss called the "Chrome Dragon." Apart from this, there's also mention of a side story coming along as well.
In an interview with Dengeki PlayStation Magazine, Kimura mentioned how story quest chapter 9 is coming first to the Vita. Along with it comes the Chrome Dragon, whom will also show up at Emergency Trials. If you are a PC player, you'll have to go on the Vita/PC shared blocks to fight him.
New scans from Dengeki were posted online that revealed some future plans for the game. Upd: They want to expand the premium features to include additional "space" for premium users to enter within normal blocks. They also want to add a feature where premium users can reuse the Aesthetics counter for a set amount of time. The magazine asked if they were going to add any new classes, races, and weapon categories. Although they plan to do so in the future, they can't discuss any details for now.
(There's some placeholder text data for Dewmans in the game, but we really don't know for sure if they're coming.)