There are only a limited number of strategies that North Korea could use to achieve sustained rapid economic development and all require access to world markets for Korean exports plus substantial investments. Those investments would be readily available to North Korea either from South Korea or China provided North Korea opened up its economy. Opening its economy and relying on large investments from abroad, however, involve substantial political risks for North Korea.
Perkins, Dwight H. "Development Strategies Available to North Korea and Their Political Risks." North Korea: Peace? Nuclear War? Ed. William Overholt. Pacific Century Institute, 2019.