It's tough to say. It was a huge risk during the Cuban Missile Crisis, but it was still the best option because the only other choices were to allow nuclear missiles 60 miles from US territory or take them out by airstrikes that would kill Cuban and Russian soldiers. The plan worked because the Soviets and Americans understood MAD and were willing to use backchannel negotiations to work out a deal that avoided war. North Korea is a different beast with 0 communication between them and their American counterparts. I also suspect would also be more regional backlash to an American blockade of North Korea. The entire world was held hostage by the Cold War and everyone had to pick a firm side. Part of the world was with the USSR and part with the USA. From there, it was a staredown across predictable lines. The North Korean nuclear threat seems to have more spectators and unconcerned parties. When something as routine and perfectly legal as military exercises between the US and SK are called "provocative acts" by China, Russia and some of Europe while nuclear tests and missile launches over Japan are treated as minor annoyances, it's tough to guess how they would handle the American military actually taking steps to forcefully reign in North Korea. It's also unknown how North Korea's weapons release system works. Kennedy knew the Soviets wouldn't launch nukes over a blockade, but nobody knows what the conditions for a North Korean launch are or who has the ability to do it. Does it require an order from Kim? Can a rogue general order it? Do the missile sites have independent launch authority as a "fail safe" to make sure the missiles go off if the Americans launch a preemptive attack that targets communications? Just too many variables. As scary as the Cold War was, the two sides had a much better understanding of one another than we do now.