I may have shared this theory on what Voldemort's plan is, but I want to toss it out there for feedback: what if Voldemort heard the prophecy and inferred that it meant that Fate wouldn't let him kill Harry until after he had "marked Harry as his equal," and his plan is as simple as fulfilling that by setting up Harry as a Dark Lord (what Voldemort interprets as "mark him as his equal") and then killing him? I feel like it has to be more complicated than that, but it seems to fit all available data.