Speaking as another former Navy submariner, I respectfully disagree. This could very well happen. I knew of at least one conventional boat that was upgraded in fairly short order. Whether or not it should have been is a separate question.
It isn't that tall of an order and the Navy certainly has talented and capable individuals that can execute a conversion...it has a pretty large talent pool to draw from...just because the "surface fleet" hasn't done it before, it doesn't mean they couldn't ever do it.
The surface fleet most certainly has done it before. U.S. surface ships used to carry nuclear Tomahawks, depth charges, torpedoes and surface to air missiles. Carriers carried nuclear gravity bombs. This all ended in 1991, but many of the same ships are still in service.
The Virginia class has 16 Tomahawk tubes, it shouldn't be a huge effort to retrofit some tubes to be capable of having TLAM/N. But would that meet the safety standards required for nuclear armaments?