Thoughts on toroidal propellers? Compared to conventional screw propellers, they can operate more efficiently and with less noise. The disadvantages are increased cost and that being quite a new technology, they haven't been tested on massive thousand +ton boats yet, just small speedboats and yachts, so it's still unknown if they will still retain their advantages when scaled up and used at lower RPM.
But assuming that they do scale up, this could be a game changer. Much less fuel consumption and quieter, the benefits for warships and ASW are obvious. It's even good for commercial ships too. I hope that China takes an interest in this particular technology and tries to scale it up for larger ships and mass adopts it. Higher upfront costs doesn't mean much, the fuel savings will eventually make up for it and the smaller acoustic signature potentially saving a warship from a submarine attack will easily justify the cost too.