For any technological advance, the counter technology adapts, so it's not very common for something to actually become obsolete.
Apparently they're modified jet-skis with cheap FPV navigation equipment.
- A peer/neer-peer adversary can presumably throw a very large number of simultaneous drones at a USN vessel. I don't know how feasible it is rustle up 10 or 100 reliable simultaneous human suicide bombers.
- The jet ski drones can surely be physically smaller than a speedboat that needs to hold a human
- The jet skis can trade some of that size back and armor themselves against CIWS etc in ways that would be less practical for a suicide boat
I don't think I'd be so worried about them surviving hits from the CIWS. On the open ocean I'd be worried about the possibility of encountering so many drones that the CIWS runs out of ammunition. In a port, I'd be worried about the practicality of using the CIWS at all, but I think the Navy can adapt.
The main thing is that the Navy were sort of deemphasizing stuff like the Phalanx on their recent ship designs, and this is the second time the past couple of weeks that I've read something suggesting they'll probably need to reverse that trend.
I still also think the front of a "jetski" drone could probably be hardened to withstand a certain amount of 20×102mm fire but, I am guessing and don't know how to determine how feasible that might be.
So I don't think you're wrong, and I think we've already found out.
A submarine with a nuclear torpedo could take out an entire carrier group.
Nuclear submarines are apparently still hard to detect underwater; but once someone figures out how to detect them, they'll be obsolete.
I think the Senior Service may be doomed.