Tabata did an interview with Dengeki and Game Watch to talk more about Final Fantasy XV. The framerate and performance of the Platinum Demo was brought up and he said that they are focusing on now optimizing the game for each platform and there should be improvements seen in the final release. King Regis' car that Noctis inherited is able to fly and Tabata said that flight won't be a requirement for the story. But did add it will grant access to new areas and will be something customized and unlocked for the car later in the game. With the focus on the car and importance to Noctis and the story, he said he wanted to put the emphasis there for flying rather than simply adding an airship because it is Final Fantasy. He said that they have no plans for PC at the moment and are focusing on the console versions, if they did have plans it would have been release near to the same time. A PC release after the console isn't out of the question though. DLC plans are still being figured out he said, but they have plans for free and paid DLC, but nothing to announce now.
Source: Final Fantasy XV PC Release In Consideration, Plans For Paid And Free DLC - Siliconera