It's a not very new but difficult field where they must hasten slowly. I imagine that powering them will be a problem so that they will be limited to especially built powerful ships [the extra weight of the big engines can be offset by eliminating heavy guns and ammunition] and nuclear powered aircraft carriers. The new Ford class has two reactors powering them.
Everyone says the next war will be fought with drones but focussed energy weapons will counter them if one that can zap a small drone at 100m can be powered by a backpack. The big plus there is that a jerry can of petrol is easier to find than more missiles when you have used your stock.
