I will not talk about the norse mythology theory and the Gentiana theory because they come from UFFXVGil. Norse theory being mine and Gentiana one being Phantom101's theory. Thanks to him to give a shoutout to us tho.
The weapon theory :
No.. these guys aren't weapons,there isn't any connection to FFVII neither does it have a connection to FFX.
Those " weapons " in the Kingsglaive movie are just creatures captured by Niflheim called DEMONS. They just serve them to destroy an empire quickly thanks to their enormous destruction potential.
Giants/Fal'Cie/Those who sit above theory :
And those giants behind Noctis in the box art are NOT those Demons,Fal'Cie,whatever things from the Norse mythology,they are the Knights of the round summoned by the Lucis Ring. They are also summoned by Nyx in the Kingsglaive movie at the final part. The Fabula Nova Crystallis mythology is GONE,so all the theories that uses something like that won't work at all.
King Regis is the final boss :
King Regis isn't the final villain,at least it's very unlikely because he DIES by the sword of Glauca,protecting everyone ( so why would he want to kill his son ? that's just stupid ) and becomes one of the Knights of the round.
ANY STRONG CONNECTION TO OTHER FINAL FANTASY :
The connection to FFVII is not possible,it was never done before and it will not be the case for this game. Because each episode is an episode of his own,using the popularity of another game ( FVII ) would be the lamest thing possible.
PROJECTION THEORY :
And oh my god.. " everything is a projection and that dude isn't Noctis "... Tabata already confirmed that it is Noctis from the future,he wanted us to see that we really spent a whole adventure with them seeing Noctis has a kid,young adult and even an adult Noct/Prompto/Iggy/Gladio 10 years older ( because yes,it is confirmed to be a 10 years time skip by the germans at Gamescom ).
That's just the point of this game,following an adventure,the adventure of this four guys. This dude is still Noctis,yes is face is not exactly the same because it's another designer,yes it has red eyes (don't forget that Noctis had red eyes when he uses his power) and YES he has the sword of his father but it's still NOCTIS LUCIS CAELUM.
As for the scene where all the team hides behind something just like what happens in chapter 0. Easy to explain,the developer team just didn't had the 3D model at this time so they made the scene with what they had,just like this scene.
Trailer ( E3 )vs Game ( Chapter 0 )
Trailer ( Reclaim your throne ) vs Game ( first chapter )
See now ? If i have to debunk more of his theories,i'll do it. I do not hate him,nor do i insult him,he has a great voice that gives you hype in an instant and that's cool. I just want people to not be excited by something that would really never happen or they would be dissapointed.