I agree with practically everything Professor Lerhe said, but you asked about NATO navies, and I think they are busy bankrupting themselves at the moment.
One of the philosophies of modern naval force organization and structure is looking for a uniformity of capability across the structure. We see that in Canada with the frigates and the future warship that would be built at Irving. We're looking for a uniformly high level of capability, as high as we can possibly afford. The problem is, the costs for new technologies as we see them today is very high. The cost for technologies that are coming is going to be breathtakingly high.
We're talking about things now like charged particle laser weapons, robotic drone swarms, and anti-ballistic missile defence systems. The cost of these things is so prohibitively high that they cannot be afforded as a common standard of capability. There has to be a lot more discrimination about how much we need and where it needs to be.
The Danes are very smart when it comes to modularity, using best commercial practices and standards for engineering. They are able to cut costs quite significantly below that of any other NATO country, so I highly recommend the committee look at Danish shipbuilding and design practices, especially when it comes to those two issues of cost and flexibility achieved through modularity. I believe this is the future in warship construction. In fact it could get to the point of what a warship actually is if you can load capability in and out of a common frame.
Eric made some very important comments about the lethality of weapon systems. If weapon systems are that dangerous, and I truly believe they are, then we have to find a better way to manage the risk and be able to produce, at short notice, replacement platforms in which to put these modules. The modules are what's expensive and what is valuable. The hull of the ship itself is not.