Phantasm 4

[Dr. Briggs]

To me, there are a few theories to what's happening at the end, but the one I'd personally think would kick the most amount of ass if Coscarelli gets around to making Phantasm V is if Reggie actually went to the past and picked a younger Mike up in that point in time.

To expand on that:
*It explains why Reggie put his ice-cream man suit back on
*It could show how Reggie died in part 1, then came back at the end. Simply put, the Reggie that snuck up behind Mike and Jody in the first spacegate scene and eventually died was the one who came back from the future. (though it would admittedly be damn hard to pull THAT off without a lot of needless filler or a downer ending)
*If it doesn't show that, it could just as well create a badass new "timeline" in which Reggie became aware of the tall man's tricks earlier and prevented him from taking Jody and trying to corrupt Mike
*It holds more potential for Mike himself, if the version in the future really was his own entity. Especially so if that Mike somehow survived getting the sphere removed from his head.