While they still have the 8"/55 automatic gun from the '70s as an off-the-shelf option, they have abandoned it in favor of the 155mm AGS, and that caliber is what seems to be the trend now, as the UK is looking at fitting some of its later DDs with such a weapon, as are other countries. One of the problems with the 8" piece is that in the 1990s, not long after the Des Moines class heavy cruisers were stricken, most of the naval 8" shells were scrapped, although some of the tooling to make new ones exists at Crane, as it was saved along with the tooling required to manufacture new 16" shells (required by Congress for the BBs). The 8" military shells which the Army has stockpiled in case the M110 howitzers ever are needed for service ae not compatible. There is als a lack of propellant, although that can easily be fixed. I think that the 8" gun really brings more potential and flexibility to the table, although there willalways be a niche for 16" guns and similar weapons, and massed naval supporting fires, which is why the battleships have survived all of these years, although in more recent times, there anti-ship capabilities and their ability to be easily adapted and to carry large amounts of modern weapons has played into it as well. If the budget hadn't been cut the way it was and the Navy's plans were not changed, they would still be on active service now.
