What is China's answer to the replicator or swarm of sea and air drone?
Are they leading the AI swarm drone field?
If you have a swarm of drone, why need destroyer or cruisers. Just build and launch hundreds at a time.
Because you need the
control of the seas.
Given how USVs do not have the necessary power generation and endurance capabilities required to operate and maintain radar and sensor systems that are comparable, if not equivalent to those on CGs and DDGs on the high seas - Large surface combatants that are in the mid-to-high 1000s of tons are still very much irreplaceable in the naval warfare of the foreseeable future.
Besides, there are different classes of USVs that are more suited for different roles. For instance, small-sized ones for reconnaissance and forward/outer-ring picket duty, mid-sized ones for proper AAW, ASuW and ASW support plus communication relay, while big-sized ones will become "wingman ships" for manned surface combatants while acting as mini-arsenal ships - And perhaps MALE/HALE UAV carriers as well.
Of course, the above classification can be quite simplistic, but the general idea still stands.
Furthermore, as USV grows bigger in dimension and displacement, increasing complexity meant that larger USVs will most likely be minimally-manned (or at most, optionally-manned) instead of fully unmanned.
Last but not least, there is also always the concern with enemy EW efforts at disrupting, jamming and spoofing allied communication networks for both manned-&-unmanned and unmanned-&-unmanned units. And with fully autonomous AI capabilities for USVs still a long way off, man-in-the-loop is still very much a must today and into the foreseeable future.