When asked about the delay, EA boss John Riccitiello said, "Essentially, step by step, [BioWare is] adjusting some of the gameplay mechanics and some of the features that you'll see at E3 that can put this into a genre equivalent of shooter-meets-RPG, and essentially address a far larger market opportunity than Mass Effect 1 did and Mass Effect 2 began to approach."
... So what does that mean? Well, mentioning that Mass Effect 2 was closer to what EA's targeting would seem to indicate more of an emphasis on action. But if the company's looking for "a larger market opportunity" a multiplayer component seems a surefire way to achieve that.
Here's hoping we remember to check this post after E3 to feel either really smart or a little sheepish about our prognosticating. Also, hello future us! Hope you're having a good summer!