I don’t think there was ever going to be a doubt if Final Fantasy, Spiderman, etc would be more popular than regular MtG. I think it’s all but guaranteed to increase player count when you have something like a popular outside IP crossed over with a different game.

Steam saw 6,000 additional active users, a 50% increase, and I honestly don’t know if that’s a signal that the crossover is a big hit, but that number seems really low overall to me. Fortnite is seeing ~6M average actives for reference. Maybe Steam doesn’t account for a very high % of the installs, so assuming a 50% increase in players in Arena is a massive jump, but to the original point, if you’re a fan of FF why wouldn’t you try a FTP game that features cards from the game? How much of it will you try is the real question.

The bigger issue that the game has had to deal with since the 90s is the complexity. I remember in the late 90s hearing store owners say things like “you have to be too smart to play Magic” and even though it’s a little silly, there is a high level of state management and knowledge needed to play the game at all. It’s quick to get a rundown of the rules, but it’s not simple to play the game. These new players are interested enough to check it out, run through the tutorial, maybe do the color challenge, but then what? It has such a high onboard cost that is very different from an RPG for FPS style game. Will they still be interested after FF rotates in 8 weeks?

These are the unanswered questions that they are gambling with at the expense of the enfranchised player base. Maybe the enfranchised players will always continue to play because they just like the game mechanics. Maybe the added players from FF and Marvel sets will outpace the existing players that quit the game. I don’t know, but just like with other technical parallels like chess or computer programming, there is a finite number of people who can play the game beyond a surface level.