ME3 lead writer Mac Walters discusses new Mass Effect
The game that Bioware doesn't want you to call Mass Effect 4 is starting to take shape, and it appears as if Shepard will not be a part of it "whatsoever," according to lead writer Mac Walters. Talking to Complex, it's clear that Bioware doesn't want the next Mass Effect game to feel like a spin-off, "without the Shepard character or the Shepard specific companions."
Walters also calls the Mass Effect 3 ending a "lesson learned," even though he is satisfied with how it turned out, and noting that there was nothing they could change once they committed to it. Either way, I'm completely cool with focusing on a new protagonist for the next iteration of Mass Effect, since Shepard has clearly ran his/her course.