What does it changes if North Korea masters building hydrogen bomb?
Does that make the country more scary than if it just mastered fission nuclear bomb?
North Korea gets more geopolitical optionality, and can maintain de facto sovereignty with a weapon of last resort. look at one of 2 (probably 3) nuclear states in the middle east, Israel, see how an ambiguous nuclear capability can protect an unprotectable position indefinitely.
otoh it upsets the balance of power in the region, and makes the good Korea almost impossible to protect. Seoul is toast in any conflict, but that won't stop the US from sewing asia and the pacific with antiballistic missile systems like pax americana johnny appleseed.