Now with new classes, new dungeons, and areas to explore!! HYPEEE

[Felis]

MSK would probably end up as maybe Chemist and something else. They said the gun class isn't what we're expecting it to be so Ranger and Corsair may not make the cut, but Chemist is already somewhat in the game because of Cid

Cid don't use guns
I think with "the gun class isn't what we're expecting" they mean the role of the class, not the class.
Like support role or tank role instead of dps role

Not to mention the Lalafel in the Thaumaturge quest IS a Chemist. He has a unique heal Water of Life or something like that? Doesn't use a gun though, and he's really just a sham class, but...it's there.

I don't know how it is in the english texts, but in the german texts it is clear that he is an Alchemist, who just wanted to be a thaumaturge like his brothers but don't have enough ether energy in his body for it.