You may have heard of Bioware teasing a new game over the last couple of weeks, and it turns out it is indeed the final part of the Mass Effect Trilogy:-

For the first time ever, the series will visit Earth, which is facing a full-on Reaper invasion following their newfound interest in the human species.
The cinematic trailer is narrated by a new character, a British sniper hiding out in London during the invasion:
Well seeing future-Earth was one of the things on my list. Now I just want an alliance with the Rachni and Geth (provided you kept them alive in the first two games), and
for the love of God some female aliens that aren't quarians or asari.
It also looks like those silly thermal clips (well, silly in the sense that identical clips were somehow still weapon-dependent) are here to stay, and possibly a new health pack system.