It would sort of be required for at least a large segment of society to be aware of it, wouldn't it? Perhaps not me personally, of course, but since I'm reasonably well-read and have never seen it even mentioned (an odd word like that will almost always catch my attention), I think it's a safe conclusion. La savate I've seen mentioned and even talked about (and you see a fair amount of it in martial-arts movies of our time), but not bartitsu. To use a natural-world approximation, while it may not be extinct, it's at least on the verge thereof, while la savate, although endangered, is a bit more present - la savate still has a sizeable number of practicioners in Europe, along with scattered pockets elsewhere, whereas bartitsu is pretty much at the scattered-pockets level everywhere.