Claim to know what?
Clive moveset in this trailer resemble some of Nero and Dante moveset, which understandable as they hired DMC staff to works on battle system. Besides every FF XIV players that watched its Live Letter knew Yoshi-P cares about player experiences and value job class as FF identity, wouldn't mind to force player playing as other characters for narrative too. So it would be amazing if he completely disregard chance to expand on it in XVI just because Clive is MC who will obtain everything.
On top of that SE does have track record of incorporating Eidolon to certain playsytle that is XIII. Assigning Odin to Lightning, modern take of Knight job; Shiva to tank-focused Snow; Bahamut to Fang, a Dragoon. So its not totally out of possibilities.
Clive have Gungnir doesn't stop other character for using it differently either.
In FF XV Noctis can use broadsword and gun, but he got nothing of Gladio's mastery and Prompto firearms knowledge (machine gun, bazooka). I believe this will be how they handle fighting-capable Dominants, Clive got their stuff but their original owner will be more capable on certain aspect if they ever became playable.
