These defections shouldn't be a surprise since younger generations of North Koreans are beginning to prioritize economic progress over loyalty to the Kim regime. By going south, they find freedom and prosperity. This could lead to reunification if the South successfully assimilates these defectors into their economy and culture.
Since the end of World War II, South Korea has been a vassal state of the American empire, unwilling to negotiate reunification peacefully. Both sides of the border want to come together, but in order to do so Washington needs to lift its hold on the region and allow sovereign countries to pursue their own policies.
There's an 8% chance that there will be a major famine in North Korea before 2025, according to the Metaculus prediction community.