Gretzky - no chance. 6 months ago, only 3 players in history (Lemieux/Orr/Gretzky) had ever topped 100 assists in a season.
To top 1963 - a player wouldn't just have to break 100 assists in a season, but do so 19 years in a row....and then still come back for a 20th season and add ~60 assists. It's video game statistics, and will never be broken. It's just impossible - sounds like video game stats.
The other 2 I feel are breakable with the right mix of longevity/consistency.
Brodeur 691 - you don't need to be a Hasek/Roy type goalie to break it. Just start early, great consistency/longevity, play for a good team. Consider Marc Andre Fleury, #2 all time with 564 wins. And Fleury has had a great career, but he isn't a top 5 goalie all time, nor even top 25. Just a decent goalie, with good longevity, playing on good teams. I know he's still ~100 wins away, but give him better health, less time missed, and do it with a slightly better goalie, and it's breakable.
Coach...this one is a bit harder because it takes longer, but it's also doable. It would take a coach starting young, and having a great career.
Paul Maurice has 880 wins. He's 57 years old. If he coaches for another 8 years an averages 45 wins, he'd top Bowman. I don't think he will - but it just shows it just takes great longevity, you don't have to be the best coach ever.
I voted goalie