FIRST OFF WARNING: FULL POST SPOILER ALERT!
Ok, I have done some further research into this and I'm starting to think that Bioware might just employ one of the greatest and bravest marketing schemes I've seen. Mike Gamble tweeted "If you know what we were planning I'd hold on to my copy of ME3". Then I noticed that the game makes a very convenient autosave just before the citadel scene. What is interesting is that the save is completely seperate from the single self overriding autosave you get throughout the game, it stays there permanently. So it insures that if need be, you could go back and choose a different option to "continue" the game if a part would be latter added to it.
Adding to this, during the discussion between Sheppard, TIM and Anderson, we notice black mist, which might be a visual representation of indoctrination, whenever TIM mentions controlling the reapers and the benefits aka giving false hope seeing as they can't really be controlled and thus allowing them to terminate the cycle unchallenged. So the theory about all of it taking place in Sheppard's head is enforced. Even more so when you think that the scene up to the beam features slow motion, a trait shared only by the other dream sequences in the game. The pistol with infinite clips also suggests that it is all a dream
And then there is the child entity. I just realized that only Sheppard has contact with him. When Sheppard meets him for the first time he suggests getting the child to safety. The child replies with a cryptic "you can't help me" statement which is quite peculiar seeing as he's a 6-8 year old. He disappears when Anderson tells Sheppard to get a move on. Getting into the shuttle, no one helps him in, he struggles to climb in himself. Soldiers, who are trained to help others before themselves, are just standing there oblivious as this kid climbs in. Nobody else seems to react to or notice him except Shepard.
During the ending, the child presents the option of controlling the Reapers as a better alternative to destroying them seeing as the later option would also destroy the geth. This more or less is a contradiction of the grey presentations that show Anderson (who represents the paragon) choosing to destroy while TIM (representation of renegade) choosing to control. Seeing as indoctrination failed during the conversation with TIM (remember the black mist) this might be the Reapers attempting to have Sheppard auto-indoctrinate himself by making him believe that the best option is to control the reapers (remember that not more then 5 minutes sooner, TIM presented the same option to which Sheppard reply that the humans can't control them and that they'd be controlled by the Reapers). So if you go past the child's indirect suggestion, choosing to destroy the reapers is the only option that sees the commander waking up under a rubble on Earth.
Leaving the "true" ending to be shown later is not something new. A few movies have done it in the past to assure that there wouldn't be any spoilers for those living in a zone in which the release date is put latter. Remember that release in Japan is on the 15th of March.
So I'm keeping my fingers crossed until then. If I'm right, I'll applaud Bioware for a very ingenious marketing strategy as soon as I'm done calling them CAPITAL ASSHOLES......JUST ASSHOLES for toying with my emotions like that
I cried at the end you know