Or has it already happened?
I've noticed a lack of traditional JJ schools over the last 10 years. Most of the ones around these days seem to be a combination of Karate, Judo, Aikido and even Bjj instead of a traditional samurai fighting style. I've also heard that in Japan, if you mention that you're looking for "Jiujitsu", the Japanese will point you to a Bjj gym. Bjj taking over the moniker of "Jiujitsu" in Japan itself..... I find that to be the irony of ironies. Here's an article about a foreigner moving to Japan, seeking to study either Bjj or JJJ, and went with Bjj because he simply couldn't find a JJJ dojo;
The Evolution of grappling in Japan: Why did I choose Brazilian Jiu-Jitsu in Japan? — Social Gelo with Angelo
Anyway, how healthy are true traditional Japanese Jujitsu systems? Is the term "Jiujitsu" destined to be taken over by Bjj?
Japanese jujujtsu is and has always been a mixture of Karate, Judo, Aikido and BJJ techniques, although the tendency is that they can't do either one properly.