So… this is a rumor, but it was leaked in a very convincing way so it seems likely that this is the story for the next Mass Effect game. Read at your own risk:
The next Mass Effect game takes place in the Helius Cluster (a cluster of 100s of solar systems in the Andromeda Galaxy), far removed by time and space from Commander Shepard’s heroic acts and the final events of the Mass Effect trilogy. You are a pathfinder, a combat trained but un-tested explorer leading an expedition into the Helius cluster to establish a new home for humanity. As you explore this sprawling series of solar systems (over 4x the size of Mass Effect 3), collecting resources and building colonies, you will encounter the savagery of untamed lands in the form of cut-throat outlaws and warring alien races. To survive and colonize the wild reaches of space, you will need to grow your arsenal, your ship, your crew and make strategic (and often uneasy) alliances to fight against increasingly menacing foes. Along the way, you will encounter the remains of a once powerful and mysterious alien race, the Remnant, whose forgotten technology holds the key to gaining power in this region of the galaxy. As you uncover who the Remnant were, and the mysteries their ruins contain, you are drawn into a violent race to find the source of their forgotten technology that will determine the fate of humanity.
I guess that is one way to separate Shepard’s story from the new game. And also guarantees you will never run into any of his squadmates or suffer any effects depending on which ending you achieved (red, green or blue). I’m kinda disappointed, because some of the worlds were fun to visit, especially the Citadel, but I guess exploring all new worlds and all new races is cool too.