60 SSNs is right at replacement rate. Boats last about 30 years and are currently being built at 2 a year. I would say we need no less than 70 boats...there has to be some level of flexibility, for things just like what happened to Miami.
And with China becoming more aggressive, and there’s simply no slack anymore.
We were able to pull from behind strength wise in WW2 because our manufacturing infrastructure was there in almost all aspects and in multiple venues if needed. We don't have that luxury now even in non nuclear defense production. I just don't think China is going to process our needed steel or especially fuel if we came under attack. Not to mention you just don't go hire experiences ship builders off the street much less ones capable of building boats. It's the old saying practice makes perfect.