On the National Interest Blog, James Hasik points out that the idea of the Littoral Combat Ships of the US Navy was successfully implemented more than twenty years ago (and much more economically, too):
In contrast, we know it’s possible to get modularity right, because the Royal Danish Navy has been getting it right since the early 1990s. Way back in 1985, Danyard laid down the Flyvefisken (Flying Fish), the first of a class of 14 patrol vessels. The ships were intended to fight the Warsaw Pact on the Baltic — a sea littoral throughout, with an average depth of 180 feet, and a width nowhere greater than 120 miles. Any navy on its waters might find itself fighting surface ships, diesel submarines, rapidly ingressing aircraft, and sea mines in close order. On the budget of a country of fewer than six million people, the Danes figured that they should maximize the utility of any given ship. That meant standardizing a system of modules for flexible mission assignment. The result was the Stanflex modular payload system.
At 450 tons full load, a Flyvefisken is much smaller than a Freedom (3900 tons) or an Independence (3100 tons). Her complement is much smaller too: 19 to 29, depending on the role. At not more than 15 tons, the Stanflex modules are also smaller than the particular system designed anew for the LCSs. But a Flyvefisken came with four such slots (one forward, three aft), and a range of modules surprisingly broad […]
Swapping modules pier-side requires a few hours and a 15-ton crane. Truing the gun module takes some hours longer. Retraining the crew is another matter, but modular specialists can be swapped too. The concept has had some staying power. The Flyvefiskens served Denmark as recently as 2010. In a commercial vote of confidence, the Lithuanian Navy bought three secondhand, and the Portuguese Navy four (as well as a fifth for spare parts). Over time, the Royal Danish Navy has provided Stanflex slots and modules to all its subsequent ships: the former Niels Juel-class corvettes, the Thetis-class frigates, the Knud Rasmussen-class patrol ships, the well-regarded Absalon-class command-and-support ships, and the new Ivar Huitfeldt-class frigates.
In short, 25 years ago the Danes figured out how a single ship could hunt and kill mines, submarines and surface ships. A small ship can’t do all those things well at once, but that’s a choice in fleet architecture. Whatever we think of the LCS program, we shouldn’t draw the wrong lessons from it. Why is this important? Modularity is economical, as the Danes have long known. Critically, modularity also lends flexibility in recovering from wartime surprise, in that platforms can be readily provided new payloads without starting from scratch. Because on December the 8th, when you need a face-punched plan, you’d rather be building new boxes than new whole new ships.
Wikipedia has this image of the HDMS Iver Huitfeldt: