The U.S. Navy is working out the details on how to abandon plans to replace current destroyers and cruisers with the new DDG-1000 class ships. It's a matter of cost. The new destroyers (and slightly larger versions designated as cruisers) will cost $3-4 billion each, and that seems likely to climb even higher because of the new technologies planned for them.
The alternative is to buy some time (about a decade) by upgrading dozens of existing destroyers and cruisers. This is a bitter pill to swallow, as only seven years ago, the navy was so sure about the new ships, that it accelerated the retirement of a dozen of the 31 Spruance class destroyers, in order to save the $28 million a year it would cost to keep them in service. These ships were not just retired, they were all either broken up, or sunk in training exercises. The dozen that entered service between 1979-83 could have been refurbished and been available until 2019. That's a lost opportunity. But what can now be done is refurb the Burke class destroyers (which began entering service in the 1990s). Most of the Ticonderoga class cruisers (which entered service in the 1980s and 90s) can use the refurb as well, which could boost their service into the 2030s. More Burke class destroyers will be built, even though these now cost about a billion dollars each.
The new destroyer (DDG-1000/Zumwalt Class/DD-21/DD-X) design has a stealthy superstructure, and is as big as a battleship, at least a battleship of a century ago, The new destroyer is a 14,000 ton ship, 600 feet long and 79 feet wide. A crew of 150 sailors operate a variety of weapons, including two 155mm guns, two 40mm automatic cannon for close in defense, 80 Vertical Launch Tubes (containing either anti-ship, cruise or anti-aircraft missiles), six torpedo tubes, a helicopter and three helicopter UAVs. The cruiser version (CGN, as Congress has mandated that these be nuclear powered) would drop one of the 155mm guns, as well as the torpedo tubes, but carry more vertical cells for missiles (especially anti-ballistic missile missiles). This would be a 20-25,000 ton ship.
For comparison purposes, consider a modern ship of a century ago. Not a support ship like a destroyer, but a "capital ship." Back then, a Mississippi class battleship displaced 14,400 tons, was 382 feet long and 77 feet wide. A crew of 800 operated a variety of weapons, including four 12 inch, eight 8 inch, eight 7 inch, twelve 3 inch, twelve 47mm and four 37mm guns, plus four 7.62mm machine-guns. There were also four torpedo tubes. The Mississippi had a top speed of 31 kilometers an hour, versus 54 for DDG-1000. But the Mississippi had one thing DD-21 lacked, armor. Along the side there was a belt of 9 inch armor, and the main turrets had 12 inch thick armor. The Mississippi had radio, but the DDG-1000 has radio, GPS, sonar, Aegis radar, electronic warfare equipment and the ability to shoot down ballistic missiles.
The century old Mississippi class ships cost about half a billion dollars (adjusted for inflation). The DDG-1000 class destroyers will cost about $3 billion each, thus possessing the price, and size, the firepower, if not the name, of a battleship.
The refurb policy will cost about $200 million per destroyer (and 20-25 percent more for the cruisers). Normally, these ships get one refurb during their 30 year lives. This not only fixes lots of things that have broken down or worn out (and been patched up), but installs lots of new technology. A second refurb is expected to add another 5-10 years. But this special refurb will do more than that. The navy wants to add some of the DDG-1000 technology to these older ships. In particular, the navy wants to install the "smart ship" type automation (found in civilian ships for decades) that will enable crew size to be reduced. The "smart ship" gear also includes better networking and power distribution. In effect, the ship would be rewired. This could reduce the crew size by 20-30 percent (current destroyers have a crew of 320, with the cruisers carrying 350). In addition to considerable cost savings (over $100,000 a year per sailor), a smaller crew takes up less space, enabling the smaller crew to have more comfortable living quarters. This is a big deal as far as morale and retention (getting people to stay in the navy) goes.
Most other new items are not space dependent, except for some of the power based ones (like the rail gun). But these technologies are receding farther into the future. Right now the navy has to find a way to live within its budget, and refurbishing existing warships shows more promise than trying build affordable new ones.