Here's the latest Andromeda Initiative video. Judging by the dates everyone was born and their relative ages in promotional materials, I'm pretty sure they leave the Milky Way Galaxy before ME3, so all of the crucial stuff about the Reaper War will likely not play into ME: Andromeda. Overall, nothing of drastic galactic change happens in Mass Effect 1 and 2 that every player didn't all complete. Sovereign attacks the Citadel for everyone in ME1, and the collector threat is handled in ME2. That's about it. The resolution of the Geth-Quarian conflict and the Krogan Genophage are all issues handled in ME3. It's pretty easy for this game to sidestep the consequences of the Reaper War.