I'll preface this by saying the BTTF trilogy is my favorite movie trilogy. I'm willing to follow the "rules" that each film/trilogy/universe/etc wants to set up for itself; for example "Terminator rules, that is, it's one way only and you can't go back. This is in contrast to, say, Back to the Future rules, where back and forth is possible, and, of course, Timerider rules, which are just plain silly.
That being said, one of the things that I was unable to rectify is how Marty (and Jennifer) are able to meet their future selves in 2015. By traveling into the future, they no longer exist in 1985, and therefore do not grow old to exist in 2015. You can't visit your future self, but you can visit your past self.
I don't accept the answer that the Starlog article posits, because of the fact that I don't agree with how he thinks alternate versions of Marty and Jennifer pop up to replace the ones that travel to the future. He also makes a lot of assumptions about the motives of Marty II.