In a multiverse, multiple timelines can be canon at the same time, you just have to expect variations big and small on some characters and concepts - I really think looking into how DC comics has handled their material over the decades can help understand some of the possibilities introduced by KoF ever since it made it so Ryo and Terry had comparable ages, not to mention later stuff like NGBC, Fu'un and Buriki One characters in XI, and the MI series being its own timeline, let alone the Another World team.
I just hope they go "Marvel Cinematic Universe" style on us, as in they actually try to connect everything. It's a great way to make people hype for even things they might not like as much, since you know all works are connected.
As for what you describe for the boss, SS's Kuroko (particularly in SS2 and SS6) comes to mind as a precedent, and 3D makes it even simpler to implement - I'm not sure if it's something they're planning to bring up for later games, but the floodgates are more open than they've ever been.
Kuroko is the one who introduced me to the "Stage Ninjas" since in many Japanese stage and comedy works, the next most memorable being Sakura Taisen anime. Just the idea that you have this little guy that's working behind the scenes to make everything come together... it's kinda 4th wall breaking, and comical in a sly way.
With all the new original characters in the game along with unlikely existing characters, they're striking an interesting balance between their history and expanding the setting with new things, so I'm looking forward to some pleasant surprises.
I like that Nelson and the South American team stage bring a hint of Nature / Technology mixing together, that's currently a bit different from what you normally see in KoF.
NEST is suppose to be some big scientific evil organization, but I never felt like it was pushed well; they made super-soldiers, and these ranged from bioroids like Maxima, to people with DNA-shifted special abilities like K', but I rarely feel like it made a strong, lasting theme, that didn't eventually dilute away after a while. If Nelson is the partially "Mechanical", Bandeiras the "Traditional", I wonder if Zarina will be "Natural" member of the bunch? Or will she have something that's like a fuse between them? (Such as being a smart sciency person too, while still not wanting to totally disrespect tradition). I can't help but think she'll be a bit Elena-like, but I'd be happy to be proven wrong.
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On to the ESRB stuff (Thanks BadWolf):
One female character's special attack depicts her pulling an opponent's face to her breasts.
In game cinematic, or Climax attack for our remaining ladies?
A handful of sequences depict close-up shots of a character smoking a cigar and a character drinking from a sake bottle.
I wonder if this means Antonov obviously smoke in combat / during his CDM? OR maybe it's just due to cinematics...
Some still-image screens show drunken characters holding glasses of beer. The words sh*t, d*ck, and a*shole appear in the dialogue.
"Still Images", eh? Wonder if that's Cinematic related? Endings?
Language seems a bit less tame than usual, that, or the translation for "Weenie" just grew up a few years.