Was the ending of Star Trek: The Motion Picture (1979) written as it was to leave open the possibility of a future reappearance of Decker/Ilia/V'ger?
The final scene of the movie has the Enterprise crew apparently "moving forward" - "let's give this ship a proper shakedown" seeming to suggest that this would only be the first of more movies to come (as indeed it was).
But, was the "evolution" of Decker/Ilia/V'ger "beyond the limits of our universe" a final ending, an opportunity for a possible revisit in a later movie, or just the end of the story without any thought of what might follow on?