Remember, Squid Game is a series by Netflix. This could be a teaser for future seasons.
Netflix produced this foreign TV series. Not mini-series, series, so there should be more seasons. The ending of the first season strongly suggests that season 2 will also occur in South Korea, at least in part. Gi-hun and the police detective may both come back. The detective got his call out and we don't know if his videos and photos sent. It seems highly likely that the action will resume next season in Korea.
However, for the show to last a significant number of seasons, it will help to make the Squid Game conspiracy more far-reaching than just Korea. This will allow the characters to chase the villains around the globe and could create an opportunity for directors, writers, and actors from other countries to get in on the action.