See - because it rhymes with "war", and that's a reference to a thing a man said in a TV show 37 years ago. The ever-watchful eye-turrets of Eurogamer spotted that BioWare community manager Chris Priestly took to the studio's forums to declare calling Mass Effect 4 "Mass Effect 4" is "doing it a disservice". It's a game that "does not have to come after. Or before. Or off to the side." Meanwhile, BioWare Montreal's head Yanick Roy has explained that Mass Effect 4 could take place after Mass Effect 3.
Currently all that's known about Mass Effect 4 is that it doesn't feature Shepard, and doesn't continue or detail the previous trilogy. It seems this goes to the extent of your chosen Mass Effect 3 ending not having any influence over the tale being told, so separate is it. Said Priestly,
"We have already said that the Commander Shepard trilogy is over and that the next game will not feature him/her. That is the only detail you have on the game. I see people saying 'well, they'll have to pick a canon ending'. No, because the game does not have to come after. Or before. Or off to the side. Or with characters you know. Or yaddayaddayadda."
Yanick Roy then appeared on the forums to clarify a little.
"What Chris is saying is that thinking of the next Mass Effect game as Mass Effect 4 would imply a certain linearity, a straight evolution of the gameplay and story of the first three games. Story-wise, the arc of the first trilogy has also been concluded, and what we will do is tell a new story set in the Mass Effect universe. That doesn’t mean that events of the first three games and the choices you made won’t get recognized, but they likely won’t be what this new story will focus on."
Uh... Wait, which one then?
"In other words, because the game takes place before of after the first trilogy does not mean it necessarily is a straight prequel or sequel."
No, those aren't other words for the thing you said before! Are my choices going to have an effect or not? Do I need to keep my ME3 save games? I'M SO CONFUSED!
It makes sense that BioWare doesn't want to call Mass Effect 4 "Mass Effect 4", since they'll be hoping to pick up a new crowd in a way that higher numbers on RPGs don't tend to engender. And sure, it's not the Shepard trilogy, so it makes perfect sense to go for "Mass Effect Subtitle". But it strikes me that Roy's clarification really only serves to make things far more bemusing - our choices in the first trilogy may still have an effect? So then it couldn't take place before, could it? Unless they're introducing time travel, and they'd bloody better not be.
This is all, of course, just a symptom of BioWare's wanting everyone to know the game is happening, but not wanting to say anything about it yet. Both are obviously perfectly reasonable, but when you've a fanbase as rabid as BioWare you've got to expect every remark to be torn to pieces.
Mass Effect 4.