Dr. Ann Maria thinks so based on the down trend of the numbers of American competitors. While number of competitors is not necessarily the same thing as number of participants, its probably as good an indicator as can be found.
As a flabby, middle-aged white guy who just started Judo less than two years ago, I can certainly see why competition oriented Judo doesn't enthrall Americans, a nation of TV junkies with a special relationship to their spectator sports. But then, my interest in Judo started as a martial art and not as a sport. If randori in our club wasn't so much fun and really good exercise, I'd probably have moved on by now: throwing is a hoot but just how much of it is applicable to a street fight remains to be seen.