As a thought experiment, let's assume that Gordie Howe retired after the 1963-64 season (at the age of 35). That would be old for that era, but not particularly unusual (there were seven active players older than him that year).
Here's what his legacy would have looked like had he retired at 35 (instead of playing in the NHL until 42, spending six years in the WHA, and a final season in the NHL at age 52). For context, this means we're excluding 33% of his NHL career (578 of 1,767 regular season games) and 46% of his professional career (997 of 2,786 regular season games):
- He still would have retired as the NHL's all-time leader in goals, assists, and points in the regular season (he'd have 1,285 points - with only two players in NHL history (one being his longtime linemate) scoring more than 800)
- He still would have retired as the NHL's all-time leader in assists and points in the playoffs
- At one point, he would have had four of the five highest-scoring regular seasons in NHL history (a record that, admittedly, didn't last long, as leaguewide scoring rose dramatically soon after)
- At one point, he would have had the highest-scoring single playoff run in NHL history (by the end of the Original Six era, he would have had four 15+ point playoffs - roughly equivalent to a 30 point playoff today since there were only two rounds back then - his linemate had three and nobody else had more than two)
- He still would have won six Hart trophies (something that, in the entire history of the NHL, has only been topped by Wayne Gretzky)
- He would have been a Hart trophy finalist ten times (something that also has only been topped by Wayne Gretzky)
- He still would have won six Art Ross trophies (something that, in the entire history of the NHL, has only been topped by Wayne Gretzky - tied with Mario Lemieux)
- He still would have earned six playoff scoring titles (something that, in the entire history of the NHL, has never been beaten - Wayne Gretzky tied it, and nobody else has more than three playoff scoring titles)
Some will try to dismiss these accomplishments as being a product of a different era. There's some truth to that - but also consider this. The three best forwards of the Original Six era, after Howe, are Jean Beliveau, Maurice Richard, and Bobby Hull. Even if he retired at 35, Howe still would have won more Art Ross trophies than the three of them
combined. He still would have won more Hart trophies than the three of them
combined. He still would have earned more playoff scoring titles than the three of them
combined. On top of that, he was clearly a better defensive player than Richard and Hull, and was, at worst, equal to Beliveau.
Sure, Howe's freakish longevity allowed him to push his career totals even higher, and he was able to pick up a few more years as a Hart finalist and top-five scorer after 1963-64. But I don't think his legacy fundamentally changes if he retired at the comparatively "young" age of 35. In some ways, it may have helped, because it would have made it harder for people to dismiss him as "only" being a player who was good because he played so many years.