A lot can happen in a year, and Square Enix celebrated Final Fantasy XV's one year anniversary with an Active Time Report, revealing that more DLC episodes would be coming next year, as well as the ability to (finally) swap characters during the main game. Until now, players had been confined to the role of Noctis unless they bought and played the DLC episodes that came out post-launch, with the final one, Ignis, scheduled to come next month.
The new character swapping feature will introduce a character overlay that will make it intuitive to swap between party members. As you might surmise, the combat abilities of Gladio, Prompto, and Ignis will be taken directly from their respective DLC's, which while it looks like a sort of quiet admission that the game was incomplete at launch (which it was), it's better late than never.
If you want to check out the full Active Time Report, you can head over here.