Lucky Bancho's estimate is 900,000 characters.

It excludes free trials and bots, so if we include these it could be over a million. Would over a million surpass WoW? I don't know because I don't know their numbers.

What we can be quite sure of is that subscriptions for this game will skyrocket when Endwalker releases and this will be noticed in the game like it usually is, but it will go down as time goes on because patch hype isn't as big as expansion hype.

WoW uses a lot of dirty tricks to increase subscriptions like pressuring you to login every day to keep up and having mounts for getting a 6 month subscription, while this game encourages breaks and makes it easy to get back into endgame content. WoW has a lot more people who have gained so many achievements in it that they could not ever change to another game and have to start over, however bad it gets. This game is at a disadvantage statistically because it doesn't do these things (and never should).