It seemed like the Creator had a plan for future seasons since there were little hints to things building up in the background of the first season so I doubt there's no plan and that they're just milking it. Of course it's hard to know if it will be as good since lots of times first seasons are good because they developed the idea for a decade then when there's an opportunity for a season 2 they're not as prepared on the details.
The entire premise is already exposed, and the story complete. Any attempt at a second season is just a pointless cash grab that completely ignores the message of the show to begin with.
Thats the best thing about the foreign adaptations on Netflix. Hollywood isnt involved, the formulas are different, the bars of acceptability are different, audience expectations are really different.
While true, a lot of korean shows do become victims of studios milking the shit out of them with sequels because they became popular. Being a foreign show doesn’t exempt them from greedy studios.
I'm assuming that the season 1 MC will only be minimally involved, probably a couple of scenes at the end of the season. The teaser trailers didn't show any new scenes with him, he was only badly edited in for a second.
The teaser I was talking about was released almost two years ago. It looks like they've released a bunch more over the last months, but I don't want to get spoiled, so I can't really check which ones are good and which aren't. They're up on YouTube if you want to have a look yourself :)