I think you are missing my point. A player is only remembered if another chooses to remember them. Time is not a factor. The only factor is that a point worth remembering about the player exists. That point can occur anytime from very quickly or some time down the road for others to notice (which makes time irrelevant). What matters is the action, whether it be in game, the forums, or both. Players aren't remembered for just playing the game, they are remembered for what they did, bounties, wars, ports, piracy, activity in the forums (suggestions and what not), etc.
As for the new players, I don't expect them to know everyone, but how they know is by veterans passing down information. Someone remembered something and deemed it worthy to pass down knowledge of their actions to the next generation of players. Their actions are remembered along with their names. Remembering a name is meaningless if you have nothing to say about them.
Here lies Joe Shmoe. I don't remember anything about him or anything he did.