IMO the individual game subs in general should go in favor of just having the SE account either being free or premium where you pay a sub. The premium sub essentially giving full access to all their online games and they could even add minor perks for other titles like Outriders.

ATM Their MMO's would be FFXIV, FFXI, and DQX though DQX wasn't officially released outside Japan. However an account based sub would probably make it easier to market outside Japan opposed to the individual subs per game. I know large numbers of DQ fans in the west have been asking for the title to be localized outside Japan and I'm kind of surprised they still haven't tapped into that potential revenue yet. There was also Front Mission Online back in the PS2 days so there's definite possibilities for other online games in the future.