We have here one of those classic multi-level pronouns so common in the technique of the novel. On the surface, "this" refers to the 'narrator's' desire to see Antonia again. On another level, it refers to the whole governing conceit of the Author's Note. Politically, it refers to the coming of a true "New Era" in any essential way. And of course, as I started by saying, "this" can refer broadly to all of life. See Decoud's line, "This is life, must be life, since it is so much like a dream."