Steve Stich states at today’s Crew-9 news conference that Dragon has a new contingency capability if all 4 parachutes fail; the SuperDracos will ignite prior to splashdown.
The Crew-8 return to Earth will also have this capability.
(He said this about 20 minutes after the start of the stream.)
When composing the title of this post I nearly called this technique ‘Propulsive Splashdown’, but I didn’t remember ever hearing that term used before. (Stitch didn’t call it that, did he?)
Later I heard Stephen Clark use that term in his question. And yesterday that term was used during the launch stream. Nail and Cardman spent a minute discussing the capability: https://www.youtube.com/live/SKXtysRx0b4?t=3h29m8s (from 3:29:08)
Apparently they often abbreviate it to “prop splash”.