I think the general issue is that the overarching setting is essentially the same or very close to the original even if the details have changed. That's an implicit pact that Eliezer has essentially made with the readers.

For what it is worth, prior to the end of the series there was a fair bit speculation that either Voldemort or Dumbledore was really a time traveling Harry (this speculation seemed most prominent after book 4 before book 5 came out).

At a general meta-level I also doubt Eliezer will do anything like this because this is still to a large extent Eliezer's vehicle for trying to illustrate concepts about rationality and that sort of plot line would seriously distract from such a goal.