The Oracle did say Neo would come back... Plus Neo seems to be the reincarnation of the first one, and the one before that, etc...so why can't he come back to life?
But then that leaves questions about Smith.
Neo and Smith are an equation, balancing each other out. A positive and a negative. That's why when Neo died, the negative couldn't live without the positive. One dies, the other dies.
So if Neo returns, will Smith?