New info from SAFG (Something Awful Forum Guy), from this pge: http://forums.somethingawful.com/showthread.php?threadid=3449196&userid=0&perpage=40&pagenumber=166:
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Destroy:
1. Synthetics Destroyed. Earth Destroyed. Shepard Dead.
2. Synthetics Destroyed. Earth Devastated. Shepard Dead.
3. Synthetics Destroyed. Earth OK. Shepard Dead.
4. Synthetics Destroyed. Earth OK. Shepard Survives.
Control:
1. Assuming Direct Control. Earth Destroyed. Shepard Dead.
2. Assuming Direct Control. Earth OK. Shepard Dead.
Merge:
1. Synergy. Shepard Dead. EDI survives.
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Question: So The geth survive in the Control and Merge endings, right?
SAFG: As far as I know, yes. The Reapers are only destroyed in the... Destroy ending. In all other endings they fly away, so I see no reason why any other synthetics would be destroyed in Control or Merge.
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Q: It's made explicitly clear that the geth are annihilated in all the Destroy endings?
SAFG: I don't know for sure but I am reasonably confident that the Guardian does indeed say that the geth will be destroyed as a consequence as well. That is, assuming the geth are alive in your playthrough.
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Q: What exactly happens to Shepard in Destroy 4? Is he/she really stranded for life, all alone, on the Citadel or earth?
SAFG: From what I could tell, he revives in the ruins of London on Earth.
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Q: Haha, when I've been playing Mass Effect for too long I tend to just brainlessly click on every blue dialogue option that comes up, so I'll have to be careful here so I don't blunder into the wrong ending.
SAFG:Trust me you can't accidentally pick an ending. It's not dialogue choice. The Guardian presents you your options (could be one, could be all three) - which are in three different directions - and then tells you to make your choice. You then have to slooooooooooooooooooowly limp your hideously burned body toward whatever choice you want to make and then interact with it: either by activating it (control), shooting it (destroy), or running into it (merge).