This IT is all convoluted and complex. A good IT needs to be simple. Irgo I resent the Patrick Starr IT.
What's presented in the ME series all happened including the ending. They are all real.
Star Child is just an avatar for the controlling AI of the Reapers plucked out of Shepard's memory.
Before star child ever came up with the "kill all of you every 50000 years to save you" idiocy, another alien super intelligent race becomes aware of the goings on in the milky Way.
The say to themselves "How do we ensure these upstarts from the milky way never overrun our galaxy?" the answer is simple. Plant a virus in Star Child which gives it the super outstanding idea that it must kill all life every 50000 years to save it.
Prosper. The milky way will never reach an intelligence level capable of leaving the Milky Way.
Unanswered Question's:
How do the Asari and know to send a ship to another galaxy, and how did the milky way eventually become smart enough to defeat the Reapers.
Answers:
A 3rd race hugely afraid of the other mentioned species genetically engineers the Asari to build the sleeper ship. There is no way the Asari could naturally evolve. Some one had to make them.
They plant a genetic worm in species to find the solution to defeating the Reapers at a slow enough pace such that the previously mentioned intelligent species is unaware of the meddling.
What is to come.
The intelligent species which indoctrinated the reapers are in the Andromeda Galaxy to which the Asari sleeper ships are headed to.
The Khet are the the Andromeda Galaxy equivalent of Cerebus. ie Red shirts.
Ryder (complete with her bad hair, waxy skin and bulbous nose" and her 2 companions will defeat the intelligent species which indoctrinated the Reapers)
he ending of the 3rd MEA game will have an equally stupid ending where the third super intelligent race is reveled.
Bioware have had this planned from the start. An inner voice after lack of sleep topld this to Patrick Star in a dream and it is now posted on the internet so it's true.
As an aside, I just wanted to mention that Bioshock Infinite's ending is actually worse than ME3's ending. ME3's ending just requires stupidity. BioshockI Infinite's ending is not possible whith the Physics of Multi universe theory.