I watched Jessecox and JP's stream watchparty, but then I checked out some other FFXIV streamer reactions. It was painful to watch all the youngins not know what the fuck the Lunar Whale was, or who Edge/Rydia/Rosa were lol
I don't think they specifically said Zenos would be the new melee class, he could be anything? Corsair does make sense with Thavnair being a focus and works well with the shirt. Someone on reddit made a more complicated relation, with the director of the movie being named Julien Temple(remember they teased Samurai with Sam Raimi, the director of Spiderman), so the class being Templar instead, which would potentially fit Zenos better but again not sure Zenos has to be the new class specifically, he could just be whatever. If anything since the CGI hero is now Paladin, he could be Dark Knight and channel Zodiark's power or some bullshit.
Paladin on the moon is basically Cecil from FFIV - Dark Knight that became a Paladin, so fits perfectly with Shadowbringers -> Endwalker since they are going hard on FF4 themes.
Typically they have one major character be a new class in the game. We can rule out all the recent ShB changes for characters. Einstinien will stay a dragoon (Kain in FF4, need to keep that parallel). They said Alisae is staying a Red Mage. Alphi is a sage now.
Zenos would be a logical choice, because he drops his weapon at the end of 5.4 and says he needs something new. A 'Reaper' class would fit with Zenos: Death, likes melee, and Scythes havent been used much in the game outside of a couple items
They could also drag Gosetsu out of the attic. If you recall, he decided to stop being a samurai, so they could always bring him back and make him the new class. This game loves bringing back older characters and he has been MIA since Stormblood.
Class possibilities:
Corsair: Maybe, but aren't they more strongly associated with pirates? Pistols and swords mix up, but doesn't fit well with a melee DPS since pistols are their signature weapon
Templars: They would basically be DPS Paladins? Could maybe be a hammer class, since hammers really havent been used at all outside Nero and Gaia. This would actually fit well with the Gosetsu idea also, since him hauling around a giant ass hammer would fit his look
"Reaper"/Scythe class: Probably the best Zenos class. Hasn't really been a FF class for this before, but would suspect it to be an edgelord DPS. Harder to "lore" this to a WoL class, though, unless Zenos just ripped it off from someone else (like he did with Samurai)
Something Magitek: Garlemond fits into this, so maybe they could do some manner of techno melee? Like a magitek whip or something?