Originally Posted by Michael J Fox is Canadian
Exactly. It clearly is the most likely future up until Marty avoids the race hence why doc travels to 2015 multiple times and everything plays out the exact same way until he actually makes a change. Marty or Buford or Biff easily could have died in many of their encounters for the remainder of the films, that would have avoided that 2015 but it doesn't. That version of 2015 has been avoided similar to how the current version of 1985 is altered in the Biffhoric timeline and later returned. But their clearly is evidence that the 'other' marty we see in 1955 is from the original timeline as well (seems to go through the same fading, also I'd think his last conversation with George and Lorraine would go differently if he's from the Biffhoric timeline where George dies in 1973.
Agreed. The 'other' Marty in 1955 IS the original Twin Pines Marty from BTTF1. Just like Old Biff is from Lone Pine 2015. And no matter how much the timeline is changed, this will ALWAYS be the case.
So, in the final timeline, in 1985, Marty grew up with successful parents...and in 2015, he became a successful rock star. However, the time traveling Marty in 1955 would remember growing up with loser parents, and Old Biff in 1955 would remember Marty being a loser who 'flushed his life down the toilet' in 2015...