Bioware said "Don't call it Mass Effect 4" They said it would actually be a reboot in an alternate universe. Like, Shepard's journey is over, it's time to be somebody else. But still, amazing Salarian! Gives the nerd species a Krogan style!
There can always be bigger, trust me. Have you played the Crysis series? Crysis 1 you end up finding aliens that have been here for millions of years. Then in C2 you find out that the earth is like a garden, the aliens are the gardeners, and humans are pest in the proverbial garden. In Crysis 3, the gardeners have been taken down by the pests, so now the owners of the garden come to investigate. My point: the boss will always have a boss, and so on and so on.
the reapers are this force that systematically harvested intelligent life for millions of years. and the 3rd game is a galactic scale battle of you fighting that force. im just to excited to see what we will be going up against. you said mass effect 4 is in a alternate universe? it's not thousands of years later after what took place in 3?