Bobby Orr spent most of his NHL career playing for the Boston Bruins, but it didn't have to be that way. IIRC, Orr grew up as a Toronto Maple Leafs fan along with the rest of his family, and reflecting back years later, Orr said that he was sure he could have ended up as a Leaf if they had shown the same interest in him towards his parents as the Bruins had. So, lets say the Leafs manage to sign Orr to a contract, and he starts laying for them during the 1966-67 season. How would the history of the Leafs and Bobby Orr be different if that happened? What about the history of the NHL and hockey in general?
Also, just as a side note, this probably means the Oshawa Generals might not come back, since IIRC, they were set up by Boston specifically with the intention to help young Orr along.