The Expendables/WMG

There will be a sequel, but it won't start filming before the end of the year
So that Arnold Schwarzenegger can have a real role, as then both he and Stallone will lead a team of mercenaries and compete with each other. And then truly the fans, nay, the world of Men shall rejoice.
 * Slated to come out in the second half of 2012. Arnold is confirmed.

Trent Mauser was just a cover name for Dutch
Arnold is playing the same role he did in Predator, and is no longer taking mission in South American jungles after the last one didn't go so well.
 * You do realize this means we'll have the Expendables fighting Predators eventually, don't you? AND IT WILL BE AWESOME.

Yin Yang is the last descendant of Nameless
After sparing the life of Emperor Qin and getting killed anyway for making the attempt, Qin decided to honor the man by burying him with honors and marking the tombstone with his own birth name - Yin Zheng. He's killed off the only remainder of his innocence and the last shred of the man he used to be.

In the Sequel, Schwarzenegger will reappear with his own team of mercenaries, consisting of...
Danny Trejo, Kurt Russell, 50 Cent, Steven Seagall, and Jean-Claude Van Damme. (See the What Might Have Been entry on the main page.)
 * Needs a token Asian - Donnie Yen? Tony Jaa?
 * Neither has the American name recognition of Jackie Chan.
 * Tony Jaa had a Start of Darkness-esque role in Ong Bak 2, maybe he'd be fine with the role of The Dragon. If so, he could possibly be the first person to kill off an Expendable.
 * Needs more Rock.
 * To make this even better, they will be pursued by a brutal team of CIA killers who have decided that the Expendables are too Badass to live. The leader of the team will of course be Mr. Church. Melee a Trois, you gotta love it.
 * Chuck Norris, since he's a devout Christian in Real Life, will play the minor role of Badass Preacher of the church where the trio met. His screentime will be short, but it will include one of the sequel's Crowning Moments of Awesome. Presumably him going all Crouching Moron, Hidden Badass on some mooks or thugs. Or something like this: the trio meets again in the church, but this time a fight is about to break out, until Chuck appears and subdues them with a hammy "THOU SHALT NOT FIGHT ON HALLOWED GROUND!" (roundhouse kicks optional). If I could find it, I'd put here a link to a photo of Chuck Norris in a cassock from Firewalker.
 * Chuck Norris should be the Affably Evil Big Bad. And kung fu fight entire Expendables teams singlehandedly.
 * Chuck Norris has commented that he'd feel inadequate among such famous action stars, and as such doesn't really intend on joining the cast.
 * Inadequate!? Does Chuck Norris have any idea who Chuck Norris even is??
 * Looks like Chuck Norris changed his mind, as he's in the movie in some form.
 * Bruce Campbell has to be in there somewhere. How about as a retired, over-sexed former CIA agent who has information that one of the teams need. There will be a shootout where Campbell casually kills a half dozen crazed killers and picks up chicks at the same time, spouting one-liners throughout.
 * And this exchange must occure:
 * Nude Girl who's life he saved: Thank God I was with a good guy like you.
 * Campbell: Good, bad, I'm the guy with the gun.
 * ... no.

Ross is a Time Lord who's gone insane and he's hallucinating everything that takes place in the film as he slowly starves to death in a broken-down TARDIS

 * Because no WMG page is complete without morbid dying dreams and references to Doctor Who.
 * Alternately, they're all a group of surviving Time Lords that the Doctor hasn't discovered because he's been too busy dealing with his own (and his companions') issues.

Samuel L. Motherfucking Jackson will make a surprise appearance in the sequel.
He's one of the few action stars they HAVEN'T mentioned. Stallone's obviously keeping him in reserve.

The last scene is a kind of shared Dying Dream.
Explaining why Gunnar is Back From the Dead, Christmas manages to hit the target, etc.

Expendables takes place in the same universe as Burn Notice
Just thinking...this would be an awesome way to shoehorn Bruce into this one.

Barney Ross is the estranged son of General "Thunderbolt" Ross.
This would make him Betty Ross's brother, and The Expendables part of the MCU.
 * And then we could get that Samuel L. Jackson cameo mentioned above.
 * Nick Fury meets The Expendables and recruits them for a team-up with The Avengers. Yes. The only thing I fear about that is that the world might explode from the sheer awesomeness.