You should read the NY Observer’s trash of the film:
http://www.observer.com/2009/movies/about-terminator-salvation-ending

“The theatrical ending, however, is in stark contrast to the original. In that version, Connor actually dies, and his fellow Resistance compatriots decide to take his face and graft it onto Marcus Wright’s robotic body. But then Marcus awakens, looking like John Connor, and kills everyone in the room. The machines win. Now that’s an ending! But since it so diametrically opposed the canon established during the previous movies, the geeks revolted when it was released onto the Internet just under a year ago.”

Ha ha. Anyway, I’m personally looking forward to future versions of the T franchise.

From McG on the original ending:
“Connor dies, okay? He’s dead,” McG continues. “And Marcus offers his physical body, so Connor’s exterior is put on top of his machine body. It looks like Connor, but it’s really Marcus underneath. And all of the characters we care about (Kyle Reese, Connor’s wife Kate, etc.) are brought into the room to see him and they think it’s Connor. And Connor gets up and then there’s a small flicker of red in his eyes and he shoots Kate, he shoots Kyle, he shoots everybody in the room. Fade to black. End of movie. Skynet wins. F— you! It’s the most nihilistic thing of all time. And Christian went f—ing crazy, of course. He was insistent that it be done that way! He wanted the bad guys to win! Can you imagine the oxygen going out of the theater?! What just happened! It would piss you off! But maybe two years from now, you’d think it was ballsy. But in the end, it just felt like too much of a bummer.”

For the record, I thought the ending was lame. Bale should have died.