Looks like Shepard will be present in Mass Effect 3, providing nothing horrible happens during Mass Effect 2.
According to BioWare’s Casey Hudson, Shephard can be killed in Mass Effect 2, but will return for the third and final game – just not as you would think.
“If your Shepard dies in the end of Mass Effect 2, that’s the end of him/her,” Hudson told IGN. “In that case, you can play Mass Effect 3 as “a” Shepard – just not “your” Shepard. As in real life, not being able to keep living is really the main down-side of death.
“So if you care about playing the next game with your character, make sure you survive this one.”
More through the link.