Recent technological advances still favor the sea-based leg of America’s nuclear triad.
www.defenseone.com
The issue is we can’t predict technological change to the point relying solely on the SSBN force for deterrence is prudent in the coming decades.
And none of the Cold War-era analysis regarded ICBM delivery of RVs for ocean bombardment as "a costly engineering challenge.”
The article he cites was about RV delivery in a retaliatory attack on a sub that had launched a LY warhead where the sub
has crash dived and sped away after launch.
The survivability was staked on the high probability of location uncertainty combined with a large number of SSBNs at sea and a large
number of tubes each such that even the loss of several boats still meant the adversary was still faced with a very large second strike
capability.