My first thought was about how a guided torpedo at those speeds means whatever you shoot at is dead with no recourse. Now a military submarine using the tech might be questionable since I cannot imagine this permits one iota of stealth (or detection outside the bubble for that matter).
Explosions underwater are already worse than in air due to the containment provided by the water. If you can lob a high supersonic torpedo at a carrier from range, it is dead - just plain, no bones about it dead. If you can get the range on such a torpedo up to maybe 100 miles or so, no surface vessel is safe.
This tech has very disturbing possibilities when it comes to the balance of sea power.
It would be a MAD type scenario because you would know the firing point and be able send a response torpedo towards it.
I think you nailed it here. The first practical use is as a weapon. If it’s already being spoken of in a civilian type application, how far along is the weapon?
The Russians have had torpedoes based on this tech for years.