Guys, I know some of you have already dismissed this theory, but this guy has just opened my eyes. If true, it makes so much more sense, and it's a genius call on BioWare's part.
We haven't even reached the fucking end yet.
Proof endings were 'indoctrinations/visions/dreams'.
Main points:
- Shepard is in space at the end (when talking to Space-Casper)
- The 'control the Reapers' choice is depicted as the 'Paragon' option
- If the 'destroy' option is chosen, 
the kid vanishes instantly (perhaps breaking indoctrination?), and then this leads to the bonus clip at the end of Shepard breathing.
- The 'breathing' segment obviously takes place on Earth.
Fuck.