Just this morning in a letter to the public, GM of BioWare Edmonton Aaryn Flynn made several things about Mass Effect crystal clear. First, he congratulated the producers on 8 years of game content, which made me feel rather old, but honestly wasn't all that important.
Flynn made the decision to confirm two separate things within the Mass Effect Universe. First, he announced the upcoming Omega content, that is scheduled this fall. Little is known about the Omega DLC, other than what the name itself implies and the assumptions that can be made from the recently leaked image. The picture of several people watching a demo of new Mass Effect 3 content hit reddit a few days ago and was the subject of quite a few rumors up until today, including the assertion that the new DLC will allow players to invade and recapture the Omega Station from either Cerberus or The Reapers. BioWare has now confirmed that the new Take Back Omega DLC will be coming this fall, but has not given any hints as to whether or not it will be the last DLC available.
Now for the best part: Flynn has announced that, "the Mass Effect universe is vast, and Casey and our teams have plans for another full game. Where to go next?" This statement doesn't give us much to go on, but it is good news, as it lets us know that BioWare has every intention of further developing the Mass Effect universe. Even cooler, Flynn hints at the idea that the next installment will be entirely different from anything we've seen before, even going so far as to welcome players' ideas. In short: they don't know what Mass Effect 4 will be, but they know it is coming.