Hints at new class? Maybe?

[Popotato]

I think it will probably be a Gunblade class, mainly because

"Shadowhunter" had a unique stance for a gunblade wielder. Usually, Gunblade users just use the PLD unsheathe stance, but Shadowhunter has a completely new, unique stance that isn't shared with any other job. This implies that they have developed some assets for a new Gunblade class.

Here's his stance: https://i.imgur.com/1Fb8GIK.jpg