The only real issue I see is, from what we have seen, the Reapers are for the moment only attacking Earth (though I wouldn't consider it a stretch to say the other human colonies would also be under attack). The focus of the game, and what I would assume your, as the player, goal is to save Earth. Humans are the ones at risk, if the fails, we as a race become one or more new Reapers. What happens to the rest of the Galaxy would be up in the air, but we wouldn't be around to care. If anyone get's turned into new Collectors, I would say it'd be the Turians.