SacremPyrobolum said:
Granted, this will be difficult. No matter how you think of them, the three endings do result in three very different outcomes for the rest of the galaxy. Unless Bioware decided to retconn two of the other decisions, they will have a hard time making essentially three different games.
Try impossible. One ending leaves the galaxy in ruins, with the geth having been wiped out, one ending leaves the galaxy in ruins with people having direct control over Reapers to rebuild the galaxy, and one ending does this weird... thing that seems to kind of Brog-ify every single sentient being in the universe. They're just significantly different to create one game around with a few branches.
You're literally going to have to write three completely different games for that, and allocate assets for three entirely different games for one game. And your publisher Electronic Arts. Not a chance in hell its happening.
I imagine that the new Mass Effect game will do one of the following:
a) Take place prior to Mass Effect (1), which could even span prior to human first contact, so it gives them a lot to work with.
b) Take place concurrently with with one or more of the Mass Effect trilogy games. Its possible to do it so that it avoids all references to major decisions Shepard makes, or make it take account for the big ones whether through a save file or just deciding them like you would if you started a new profile in ME2 or ME3.
c) Make one of the endings canon. Even if you play with the story so you don't know what endgame the game went with, you're going to have to declaratively make synthesis either canon or non-canon, because you can't hide glowing green eyeballs and omniscience away from the player unless you're playing as Space Hamster.