Moving to an 8-team system will actually trigger a dark age.

This topic comes up every time something happens with the national team. If we return to an 8-team system, far from getting better, a dark age will arrive before long.
First of all, if you reduce the number of teams, the quality of first-string games will naturally improve. This is because slots decrease and only the core talent remains. The more you reduce—to 8, 6, or 4 teams—the more pronounced this becomes. However, for the quality of a league to improve, the mid-tier and reserve player pools must be deep. The national team, by its very nature, only selects the very top few; is this truly an essential structural improvement for Korean baseball?
Returning to an 8-team system means a reduction in the total number of games. This means one-fifth (20%) of ticket revenue, broadcasting revenue, advertising revenue, sponsorship revenue, and other IP revenue will vanish. In other words, the market size of the league shrinks accordingly. Consequently, clubs will spend less money than before because it simply won't be as profitable.
The real problem starts here: the first group to be hit will be the players in the ambiguous "1.5-tier" to "2nd-tier" ranks. In other words, the layer that is supposed to serve as the backbone of the league will be crushed. This will then spread to A-tier players, while conversely, S-tier players will see even more inflated values. This is because demand will remain, but high-quality resources will become scarce.
As the league continues to shrink like this, fewer amateur players will be drawn to it. As everyone knows, parents these days are reluctant to have their children pursue sports. For parents to encourage their children to play, and for children to dream of becoming athletes themselves, there must be an incentive—and ultimately, that is money. Being a professional must be something that shines brightly. Another factor would be jobs; a way to make a living even if one doesn't become a superstar.
The reason soccer attracts amateur players like a vacuum cleaner is ultimately due to the size of its market (including overseas) and the available jobs. Baseball is only managing to hold its ground in this situation because it is baseball. But imagine if the professional league itself shrinks. What parent would go out of their way to make their child play baseball? Children themselves will choose soccer over baseball.
Of course, these things won't happen immediately. However, as 5 or 10 years pass, this negative cycle will become entrenched, and eventually, instead of a period of prosperity, a dark age will arrive in the near future. And unlike the present, where we talk about self-sustainability, we will end up like the past.