38North.org has since debunked that assessment. https://www.38north.org/2018/08/mmadden080318/
The authors pretend to have a level of certainty which is really based upon interpretation and subject to spin. At least Lewis admits that he could be wrong in his assessments. Klinger always views everything in the worst light possible. Cooling is going to be needed at Yongbyon regardless of production status.
Bruce Bennett as Rand's leading "expert" has been predicting the collapse of North Korea for years.
The administration is trying to pretend now that they didn't agree to the first two clauses of the Singapore declaration, that they papered over the North Korean requirement for a new relationship fostering peace and prosperity with the US. Pompeo recently said that North Korea needs to decide on whether it's going to make a strategic shift in its relations with the US and the rest of the world. Actually, it was Trump and Pompeo that told North Korea, the US was willing to make a strategic shift in its relations with North Korea before and at Singapore and retreated from that posture in light of the fierce institutional resistance and political criticism at home. Trump stood on the white house lawn and told the world about a declaration to end the Korean War just after he met with Kim Yong Chol before the Singapore summit. John Bolton repeatedly goes to the media and states that Kim Jong Un said they would denuclearize within one year at the April 27 meeting with Moon Jae In. The first time he said this, the Blue House in South Korea reported that there was no factual basis to the claim.
Now faced with mounting criticism and an upcoming election, Trump, Pompeo and others return to well worn hard liner path that has never worked.
This is a much better article that shows greater insights into what the issues are:
https://www.vox.com/2018/9/6/17827100/north-korea-trump-kim-south-nuclear