The two MiG-21s that were intercepted on their way from Cuba to North Korea should not concern anyone: the bird is the airborne equivalent of your grandfather's old Buick.
Yes, the MiG 21 is no longer the scourge it used to be, especially in the hands of a North Korea (DPRK) wracked to strangulation with international sanctions.
Even Grandpa's Buick is probably in better order than the DPRK's fleet of approximately 150 or so MiG 21 flying jalopies — the country's most numerous fighter jet.
Which leads us to believe that the two MiGs were destined to either be cannibalized, or set up in a North Korean propaganda museum.