I think you make good points.
However, I wouldn't count our subs out so wholesale quite yet.
We likely have more than a few tricks up our better tech and training sleeves.
Then there's our UFO and probably USO craft . . . as well as other exotic weapons.
I was once told by someone who should have known that we have at least ELEVEN different and better (i.e. more devastating) weapons systems than nukes. I couldn't squeeze out even a slight hint about what sorts.
The thing about a sub is, you don't really have to sink it. All you need to do is to disable it.
Since a submarine is already in a hazardous, somewhat tenuous, situation when submerged, disabling it becomes that much easier.
If you have weapons which will disable any submarine anywhere within a significant circumference area, then again, as I said before, you don't really have to know where it is. If you launch these disabling weapons in a tessellated clearing pattern, you can clear several miles of area and send prayers up for any underwater craft that may have been there.
That is my basic point. Today, when engaging a submarine, it is not necessary to know where it is. All you need to know is a general area, and you got it.
The bottom of the oceans is covered with trenches, mountains, and valleys. In many areas of the ocean there is only one, or one of a few, paths to travel safely when submerged. These paths can be mined with drones which will wait there until they pick up a specific audio signature. Then they will automatically activate and deploy.
I would not want to be on a submarine today, in a time of war. They are too easy to kill, even if they are sitting still hiding somewhere. It does not matter.
