I think I can explain why the Resident Evil series went from scary to action packed.
It's called "The character grew some balls".
Anyway, here's a few theories about what I think will be in Resident Evil 6, based on the trailer:
--- Leon's Scenario ---
As we (should) all know, Leon became a U.S. Agent for the President after RE2.
If I had to (bio)hazard a guess, the Prez lives, or is currently taking refuge, in this Tall Oaks place. At the very least, that helps to keep this "New Raccoon City" isolated to Tall Oaks.
This Tall Oaks place is most probably fictional, like Raccoon City. And like with all places of fiction in America, I like to think in it's Ohio.
IT'S ALWAYS OHIO!
Anyway, Leon will probably be sent in there to retrieve the prez. I believe that Leon will encounter the prez as a human there, but as the story develops, the prez will become a zombie.
Speaking of which, zombie virus outbreak. I don't believe we will have a Las Plagas/Majini hive mind group to deal with, but rather the old school zombies (but possibly stronger, or just as dumb and demeaning). I have a few theories of how that occurs, and it's all got to do with the woman.
This woman, who zombie prez (I assume it's zombie prez) attacks in a scene or two, is a researcher of a sort. I believe the reason that the prez is at Tall Oaks in the first place, is that it houses a government version of an Umbrella/Tricell/Veltro laboratory. Unlike those other places where they make BOW's, this place would try to figure out how to either destroy them, or immunise people against infection, or both, or neither.
Anyway, this dumb idiot screws up, releasing one of the BOW samples onto the poor citizens of Tall Oaks, hence infection, and therefore why she likes to break down about the whole thing.
If I wanted to (probably foolishly) pursue the identity of this woman further, I could (bio)hazard a guess and say that it could be Sherry Birkin from RE2. She's supposed to be in quarantine with the U.S. Government, due to the G-Virus inside her, which I don't think the cure in RE2 was perfect. It's possible she could be that woman (although a little too old), and that Tall Oaks is actually contaminated with a G-Virus, or an advancement of it, hence the zombie-zombie. That's a little too farfetched.
Another theory on her identity I thought of was Ashley Graham. Now, we don't know if this prez is still the same prez from RE4. Ashley Graham is the prez's daughter. If I still cling to the idea that Tall Oaks is actually a cover for a U.S. Anti-BOW research lab, it's possible to place her there.
Among other things, Hunnigan returns. I never liked her, she's like a British Sheva or something.
--- Chris' Scenario ---
WE'RE GOING AZN!!!
Or at least I like to think. I'm pretty sure there was a neon sign from a helicopter type angle that had asian writing on it. I wouldn't surprised if it was Tokyo or Osaka, I'll give a reason why at the end.
So, this is possibly the first time we will actually explore a city during a BOW siege. RE0, RE1, RE2, RE3, CV, RE4, RE:R and RE:5 have all had the areas that you do explore mostly infected already. When you watch Chris' pumping them feet down the street, there are people running for their lives. Now, I didn't pay attention, I felt it was an asian city, but I think all the people running were white.
Well, at least it could be the first time. I'm not sure whether that Terragrigia in RE:R will simply be backstory, or interactive. Even if it was interactive, is it in the thick of it, or a clean up operation?
Anyway, it looks like he too is picking up where he left off, career wise anyway. Probably still a major leader in the BSAA. Again, no definites.
So what does this scenario involve? Well, with Umbrella and Tricell buried into the ground, (and probably Veltro in RE:R) there has simply got to be another organisation calling the shots. Remember, that Irving guy in RE5 dealt with a lot of groups, and I don't think that means two (Umbrella was already dead).
And Chris is looking for a bull in a china shop, in which case the bull is the bad guys, and the china shop is this city with screaming people, BOWs and neon lights.
--- The guy I will simply call "The Merc"'s Scenario ---
So there's this guy, who looks like a generic bald hero badass that most MA15+ games are getting lately (e.g. Cole McGrath, that GTA IV guy, Nathan Hale, my Mass Effect 2 dude), and apparently his blood can cure the virus...
Before I continue, we don't know if this is merely a single virus this game is trying to deal with here. It's possible that a single virus is what we're up against, but it would be a nice surprise if more than one were hanging around.
But this badass is saying "OOOOOH, PAY ME, I NEED MUNNIEZ FOR FRIED RICE! THEN U CAN HAVE MAH MAGIC JUICE!!!"
Jerk...
He looks like he got chased by a... Tyrant/Nemesis/El Gigante/Executioner (no seriously, did you not see that random fusion there?)
And there's an albino chick with him. Possibly a new character. I doubt it's Jill, even with the ninja reflexes...
Although it could be Jill, with her ever changing face...
' (Don't hate, it's true)
I'm assuming the bad guys behind that... stalker mutant, want this guy dead. Possibly alive, who knows. All I can figure is that he's a real renegade, he won't be playing crusader or dark lord, and will probably receive some complex plot to get a conclusion. <-- (Missing the word 'decent' on purpose).
--- Game Play ---
Well, as much as I'd like to say the gameplay in this teaser was prescripted scenes, remember that MH4 was actual gameplay, even though it didn't look like it. Then again, teaser's don't usually show HUDs. Leon's 'slide below and 180 BOOM!' was pretty cool, wouldn't mind doing that to everything. When I saw Chris dive for cover, only to be pulled over the top, that's what gave me the impression that more than one virus is in this game, and it look a lot like the T-Abyss virus when it grapples you and decide to feast on, you guessed it, the neck.
--- Other Characters ---
Anyone else expecting Wesker to come back? I mean, he melted in a volcano, right? But, that guy... doesn't look like the dying type (not while this bromance is incomplete).
HUNK. The infamous Mr. Death, who also doesn't seem to die.
Jill. She's gotta be in it. I'll get to that soon.
Claire. Possible, and not because of fandom. Both Leon and Chris are in this game, and before that, she was the common link between them.
Barry 'Sandwich' Burton. Seriously, not a single line since Gaiden to make us all facepalm with hilarity? OUTRAGE! I wouldn't be surprised if he came back.
Nicholai: According to the Canon line of RE3, this Mcguffin escaped on a helicopter. If he's not in this game, he's part of Veltro. $10 says so.
--- That thing I talked about a few times ---
RE6 is so the last game in Resident Evil. I mean, Chris and Leon in the same game. That one thing that fanboys keep fighting over fulfilled.
We all know what happened last time fanboy desires were being fulfilled by Capcom. We like to call that MML3.