According to TNG Companion Wesley according to Gene Roddenberry was never supposed to be Picards son. In fact as originally written, Beverly Crusher was a very minor role, while Wesley was a main character. They were supposed to focus on how Wesley's father had died due under Picards command.
It appears as the writers fleshed out Beverly's character they decided to add a love interest between her and Picard, which is what lead many to assume that Picard was secretly the father, however, according to this book there is no mention of this ever being planned.
Basically we know from the start that Wesley was not intended to be Picards son, and we know that in the end he ended up not being Picards son. At most now we are dealing with a rumor of someone changing the back story which never panned out. As you've stated Praxis there are only mentions of this on forums, no interviews, or books containing this idea that Picard was going to be Wesley's father.